select a random sample of size 2 by writing the five numbers in this population on slips of paper, mixing them, and then selecting two. calculate the mean for your sample.

Answer:

third option

Step-by-step explanation:

(4x + 3)² = 18 ( take square root of both sides )

4x + 3 = ± [tex]\sqrt{18}[/tex] = ± [tex]\sqrt{9(2)}[/tex] = ± ([tex]\sqrt{9}[/tex] × [tex]\sqrt{2}[/tex] ) = ± 3[tex]\sqrt{2}[/tex] ( subtract 3 from both sides )

4x = - 3 ± 3[tex]\sqrt{2}[/tex] ( divide both sides by 4 )

x = [tex]\frac{-3+3\sqrt{2} }{4}[/tex] , x = [tex]\frac{-3-3\sqrt{2} }{4}[/tex]

In triangle ABC as per given measurements the measure side length BC is equal to 7.26cm (Rounding to three significant figures).

In triangle ABC,

Measure of angle A = 36 degrees

Measure of angle B = 90 degrees

length of AB = 8.7cm

Use trigonometry to solve for the length of BC.

First, Measure of angle C,

In triangle ABC,

Measure of (Angle A + Angle B + Angle C ) = 180

⇒ 36 + 90 + Measure of angle C = 180

⇒ Measure of angle C = 54 degrees

Now , use the sine function to solve for BC,

sin(C) = opposite side /hypotenuse

Substitute the values we have,

⇒ sin(54) = BC/AB

⇒BC = AB × sin(54)

⇒ BC = 8.7 × 0.834

⇒ BC = 7.2558

Rounding to three significant figures, we get,

BC ≈ 7.26 cm.

Therefore, the measure of length BC in triangle ABC is equal to 7.26cm.

Learn more about triangle here

brainly.com/question/13664253

#SPJ4

The above question is incomplete, the complete question is:

ABC is a right-angled triangle. Angle B = 90. Angle A = 36. AB = 8.7 cm. Work out the length of BC. Give your answer correct to 3 significant figures.

a.  The cost of renting the gym and paying for supplies, which is $300. b. $10, c. y = 10x - 300 d. $200 e.  30 tickets f. the slope of the line is 1/6.

The slope of a line is the ratio of the change in the y-coordinate to the change in the x-coordinate. It represents the rate of change of the line. A positive slope indicates that the line is increasing, while a negative slope indicates that the line is decreasing. A slope of zero indicates that the line is horizontal.

The y-intercept is the point where the line crosses the y-axis. It represents the value of y when x is equal to zero.

Linear equations can be solved algebraically or graphically. In algebra, the goal is to isolate the variable and find its value. In graphing, the equation is plotted on a coordinate plane and the solution is the point where the line intersects with the x- or y-axis.

a. The constant in this situation is the cost of renting the gym and paying for supplies, which is $300.

b. The rate in this situation is the cost per ticket, which is $10.

c. Let x be the number of tickets sold and y be the total profit. The linear equation that represents this situation is:

y = 10x - 300

d. If Amanda sells 50 tickets, then the profit is:

y = 10(50) - 300 = $200

e. To break even, the profit must be 0. So we can set y = 0 and solve for x:

0 = 10x - 300

10x = 300

x = 30

Therefore, Amanda needs to sell 30 tickets to break even.

f. The graph of the linear equation is:

graph{y=10x-300 [-10, 50, -500, 500]}

To calculate the slope of a line that goes through points (10, 6) and (-2, 4), we can use the slope formula:

slope = (y2 - y1) / (x2 - x1)

Substituting the given values, we get:

slope = (4 - 6) / (-2 - 10) = -2 / -12 = 1/6

Therefore, the slope of the line is 1/6.

To know more about slope  visit:

https://brainly.com/question/29181869

#SPJ1

  The decimal values:

  - Positive ratio: 0.4
  - Negative ratio: 0.4
  - Zero ratio: 0.2

To calculate the ratios of positive, negative, and zero elements in an array of integers,

Follow these steps:

1. Initialize three variables, 'positive', 'negative', and 'zero', to count the number of positive, negative, and zero elements in the array.

2. Loop through the array of integers and for each element, check if it is positive, negative, or zero. Increment the corresponding count variable accordingly.

3. Calculate the decimal value of each fraction (ratio) by dividing the count of positive, negative, and zero elements by the total number of elements in the array.

4. Print the decimal value of each fraction on a new line with places after the decimal.

Here's an example with the array [1, -2, 0, 3, -1]:

1. Initialize positive = 0, negative = 0, zero = 0.

2. Loop through the array:
  - 1 is positive, so positive = 1.
  - -2 is negative, so negative = 1.
  - 0 is zero, so zero = 1.
  - 3 is positive, so positive = 2.
  - -1 is negative, so negative = 2.

3. Calculate the ratios:
  - Positive ratio = positive / total elements = 2 / 5 = 0.4.
  - Negative ratio = negative / total elements = 2 / 5 = 0.4.
  - Zero ratio = zero / total elements = 1 / 5 = 0.2.

4. Print the decimal values:
  - Positive ratio: 0.4
  - Negative ratio: 0.4
  - Zero ratio: 0.2

To know more about Array of Integers:

https://brainly.com/question/15048840

#SPJ11

Using graphs,

The ordered pair, (6,15) represents here the cost of 6 pounds of noodles that is $15.

A structured representation of the data is all that the graph is. It assists us in comprehending the info. Data are the numerical details gathered by observation. Data is a derivative of the Latin term datum, which means "something provided."

Data is continuously gathered through observation once a research question has been formulated. After that, it is arranged, condensed, and categorised before being graphically portrayed.

Here in the question,

As we can see that the graph is a relation between the number of noodles in pounds and the cost of noodles in dollars has been given and compared.

So, as per the question,

The ordered pair that represents here the cost of 6 pounds of noodles is (6,15).

As, from the graph:

When noodles in pounds is 6, cost in dollars is 15.

To know more about graphs, visit:

https://brainly.com/question/17267403

#SPJ9

The complete question is:

the points on the graph show how much chee pays for different amounts of noodles, complete the statement about the graph

The correct interpretations of the given quantity are C and E.

C. Your daily viewing time is greater than 90% of all Netflix users.

E. 90% of all Netflix users viewing times per day are less than your daily viewing time.

To understand the correct interpretation, we need to first understand what the 90th percentile means. It refers to the value below which 90% of the data falls.

If your daily viewing time is in the 90th percentile of all Netflix users, it means that your viewing time is greater than 90% of all users. In other words, only 10% of users watch more Netflix than you, and your viewing time is greater than the viewing time of 90% of users.

Therefore, options C and E are the correct interpretations.

Learn more about Interpretations:

https://brainly.com/question/1449267

#SPJ4

Complete Question:

Suppose the amount of time (in minutes) per day that you spend watching Netflix is in the 90th percentile of all account users. Which interpretation(s) of this quantity are correct? Select ALL that apply.

A. You spend approximately 90 minutes per day watching Netflix.

B. 90% of all viewers spend more time on Netflix per day than you.

C. Your daily viewing time is greater than 90% of all Netflix users.

D. There is a 90% probability that a randomly selected viewer spends less time than you watching Netflix per day.

E. 90% of all Netflix user viewing times per day are less than your daily viewing time.

F. 90% of all Netflix user viewing times per day are less than or equal to your daily viewing time.

The probability that the next customer will pay with cash or a credit card is: 0.90

What is the probability?

The probability that the next customer will pay with cash or a credit card is the sum of the probabilities of these two events occurring.

The probability of the next customer paying with cash is the ratio of the number of customers who paid with cash to the total number of customers:

P(cash) = 122 / (122 + 14 + 4) = 0.870

Similarly, the probability of the next customer paying with a credit card is:

P(credit card) = 4 / (122 + 14 + 4) = 0.029

Therefore, the probability that the next customer will pay with cash or a credit card is:

P(cash or credit card) = P(cash) + P(credit card) = 0.870 + 0.029 = 0.899

Rounding this to the nearest hundredth, we get:

P(cash or credit card) ≈ 0.90 (rounded to the nearest hundredth)

To know more about probability, visit:

https://brainly.com/question/11234923

#SPJ1

10-hole harmonicas, which can produce a wider range of notes and are more commonly used in professional music settings.

An equation is a statement that expresses the equality of two mathematical expressions using mathematical symbols such as variables, numbers, and mathematical operations. The equality is represented by an equal sign "=" between the two expressions. Equations are used to represent mathematical relationships and solve problems in various fields such as physics, chemistry, engineering, and economics.

Given by the question.

The terms "6 holes and 1/2" and "10 holes" are often used to refer to harmonicas, which are small wind instruments that produce sounds when air is blown into or drawn out of them.

The main difference between a 6-hole harmonica and a 10-hole harmonica is the number of holes on the instrument. As the name suggests, a 6-hole harmonica has 6 holes, while a 10-hole harmonica has 10 holes.

In addition to the number of holes, the two types of harmonicas may also differ in their size, range, and the specific notes that they can produce. 6-hole harmonicas are typically smaller and produce a more limited range of notes compared

To learn more about equation:

https://brainly.com/question/1529522

#SPJ1

The machine part's maximum possible size is 13.5 + 0.07, or 13.57 millimeters.

Two mathematical expressions are shown to be equal in an equation, which is a declaration that is frequently denoted by the equals symbol (=). It implies that the amounts or values represented by both formulations are the same. Equations are a useful tool for representing the relationships between variables and for problem-solving because they allow you to identify the values of the unknown variables that the equation requires. They are frequently applied in the domains of math, physics, engineering, and other sciences as well as in daily activities like budgeting, time management, and cooking.

given

The following absolute value equation could be used to calculate the machine part's height's maximum and minimum values:

0.07 for |height - 13.5|

The machine part's minimum possible size is 13.5 minus 0.07, or 13.43 millimeters.

The machine part's maximum possible size is 13.5 + 0.07, or 13.57 millimeters.

To know more about equation visit:

https://brainly.com/question/649785

#SPJ1

Matt has 6 dimes coins and 24 nickel coins.

The solution to this math problem is as follows:

Let the number of dimes be x Matt has 4 times as many nickels as dimes therefore the number of nickels is 4x. The combined value of the coins is 180 cents. We know that a nickel is worth 5 cents and a dime is worth 10 cents. Therefore we can write an equation:10x + 5(4x) = 180

Simplifying,10x + 20x = 180

30x = 180

x = 6

Therefore there are 6 dimes and 4 * 6 = 24 nickels.

To learn more about "Combined value": brainly.com/question/14293955

#SPJ11

Interposition refers to the belief that a state has the right to intervene between the federal government and its citizens to protect them from unconstitutional laws, while nullification is the belief that a state has the power to declare federal laws null and void within its borders.

Interposition and nullification are two theories of state sovereignty that were debated during the early years of the United States. Interposition refers to the belief that a state has the right to interpose itself between the federal government and its citizens to protect them from unconstitutional laws.

On the other hand, nullification is the belief that a state has the power to declare federal laws null and void within its borders. The main difference between interposition and nullification is the extent of state power they propose.

Interposition allows a state to protect its citizens from unconstitutional federal laws, while nullification allows a state to effectively veto a federal law within its borders. While interposition has been recognized as a legitimate theory of state sovereignty.

Nullification has been largely discredited and is not recognized as a valid legal doctrine under the U.S. Constitution.


To know more about federal laws, refer here:

https://brainly.com/question/28498485#

#SPJ11

Answer: :)

Step-by-step explanation:

2x + x = 21

Lets x = the amount of time Lilly played

2x = 2 * x = the amount of time Paul played (2 times the amount Lilly played)

:)

Answer:

3s+7.99=71.83

Step-by-step explanation:

Answer:

The slope is "m"

m= -5

Step-by-step explanation:

x-- Axis interception points of x- 2x - 4x +8 ( 8 over 5, 0)

y-- Axis interception points of x - 2x - 4x +8 (8,0)

x-2x-4x+8

y=-5x+8

we would need at least 678 freshmen to make purchases to estimate the average amount spent on books in their first year with a 90% confidence interval and a margin of error of $2, assuming the estimated standard deviation of the amount spent is $30 based on last year's book sales.

To calculate the number of observations required to achieve a 90% confidence interval with a margin of error of $2 and an estimated standard deviation of $30, we can use the following formula:

n = (z * σ / E)^2

Where n is the number of observations required, z is the z-score for the desired confidence level (in this case, 90%, which corresponds to a z-score of 1.645), σ is the estimated standard deviation ($30 in this case), E is the desired margin of error ($2 in this case).

Substituting the values given:

n = (1.645 * 30 / 2)^2 = 677.89

Rounding up to the nearest integer, the number of observations required is 678.

To know more about confidence interval:

https://brainly.com/question/29680703

#SPJ4

The average number of exclusive relationships Duke students have been in is between 2.972 and 3.428.

So, we can estimate with 90% confidence that the average number of exclusive relationships Duke students have been in is between 2.972 and 3.428.

Learn more about average number

brainly.com/question/16956746

#SPJ11

2 and 2/3 divided by 6 equals 4/9.

So, 2 and 2/3 divided by 6,

we can simplify it step by step as follows:

First, we need to convert the mixed numbers 2 and 2/3 to an improper fraction:

2 and 2/3 = (2 × 3 + 2) / 3 = 8/3

Therefore, the expression becomes:

8/3 ÷ 6

To divide fractions, we need to invert the second fraction and multiply:

8/3 ÷ 6 = 8/3 × 1/6

Simplifying the multiplication of fractions:

8/3 × 1/6 = (8 × 1) / (3 × 6) = 8/18

Now, we can simplify the fraction 8/18 by dividing both the numerator and denominator by their greatest common factor, which is 2:

8/18 = (8 ÷ 2) / (18 ÷ 2) = 4/9

Therefore, 2 and 2/3 divided by 6 equals 4/9.

To know more about the division visit:

https://brainly.com/question/21416852?

#SPJ1

===================================================

Reason:

Dividing by 11 leads to a repeating fraction, so that rules out 16/11. The decimal value 1.45 doesn't repeat and is instead a terminating decimal.

It's a bit interesting that 16/11 = 1.454545... so if we were to round it, then 16/11 is approximately 1.45; however, 16/11 is not exactly 1.45

As for 131/90, that won't work either because 9 is a factor of 90. Dividing by 9 leads to a repeating fraction.

131/90 = 1.455555...

This rounds to 1.46

-------------

Here's one way to determine what fraction is equal to 1.45

1.45 = 1.45/1

1.45 = 145/100

1.45 = (29*5)/(20*5)

1.45 = 29/20

You can use a calculator or long division to see that 29/20 converts to 1.45

[tex]3\frac{3}{4}[/tex] feet is 2.25 feet. 7.75 feet of plywood left out of 10 feet when [tex]3\frac{3}{4}[/tex] feet of plywood is cut off.

[tex]3\frac{3}{4}[/tex] feet is a mixed fraction, first we need to convert it into a fraction and then we need to find the point value of the number.

therefore [tex]3\frac{3}{4}[/tex] feet = 3 x 3 / 4

= 3 x 0.75 = 2.25 feet

now we need to find the plywood left when [tex]3\frac{3}{4}[/tex] feet is cut from 10 feet,

therefore, now that we know [tex]3\frac{3}{4}[/tex] feet is 2.25 feet we can subtract it from 10 we get:

10 - 2.25 = 7.75

therefore, we know that there is 7.75 feet of plywood left out of 10 feet when [tex]3\frac{3}{4}[/tex] feet of plywood is cut off.

To learn more about fractions, click here:

brainly.com/question/10354322

#SPJ4

The model will be as follows: y = b0 + b1x1 + b2x2 + u

To write a model that allows the variance of u to differ between men and women, the best option is to use the heteroscedasticity model. This model will enable the variances to differ between the genders without depending on other factors.

The model will be as follows: y = b0 + b1x1 + b2x2 + u, Where y = dependent variable, b0 = constant or intercept, b1 and b2 are the coefficients for the independent variables x1 and x2, u = error term for the model. However, this model does not allow the variance of u to differ between men and women.

To achieve this, we need to modify the model to allow the variance of u to differ between men and women. This can be done by using the weighted regression model. The model will be as follows: y = b0 + b1x1 + b2x2 + u, where y = dependent variable, b0 = constant or intercept, b1 and b2 are the coefficients for the independent variables x1 and x2, u = error term for the model.

The weights can be represented as: wi = 1/σ^2i, where: wi = weight for observation, iσi = standard deviation of the ith observation. This model will allow the variance of u to differ between men and women without depending on other factors.

To know more about variance refer here:

https://brainly.com/question/13708253

#SPJ11

The two triangles in the following diagram are congruent. The proofs are mentioned below.

SSS (Side-Side-Side)

If all the three sides of one triangle are equivalent to the corresponding three sides of the second triangle, then the two triangles are said to be congruent by SSS rule.

SAS (Side-Angle-Side)

If any two sides and the angle included between the sides of one triangle are equivalent to the corresponding two sides and the angle between the sides of the second triangle, then the two triangles are said to be congruent by SAS rule.

ASA (Angle-Side- Angle)

If any two angles and the side included between the angles of one triangle are equivalent to the corresponding two angles and side included between the angles of the second triangle, then the two triangles are said to be congruent by ASA rule.

AAS (Angle-Angle-Side) [Application of ASA]

AAS stands for Angle-Angle-Side. When two angles and a non-included side of a triangle are equal to the corresponding angles and sides of another triangle, then the triangles are said to be congruent.

AAS congruence can be proved in easy steps.

RHS (Right angle- Hypotenuse-Side)

If the hypotenuse and a side of a right- angled triangle is equivalent to the hypotenuse and a side of the second right- angled triangle, then the two right triangles are said to be congruent by RHS rule.

Hence, the two triangles in the following diagram are congruent.

Learn more about Congruence:

https://brainly.com/question/20521780

#SPJ1

Answer:

a. The triangular prism has 5 faces, 9 vertices, and 12 edges.

b. To find the volume of the packaging, we need to multiply the area of the base (an equilateral triangle) by the height of the prism.

The area of an equilateral triangle with side length 3.6 cm is given by:

$A = \frac{\sqrt{3}}{4} s^2 = \frac{\sqrt{3}}{4}(3.6\text{ cm})^2 \approx 5.270\text{ cm}^2$

So, the volume of the Toblerone packaging is:

$V = Ah = (5.270\text{ cm}^2)(21\text{ cm}) \approx 110.59\text{ cm}^3$

Therefore, the volume of the Toblerone packaging is approximately 110.59 cubic centimeters.

Under the null hypothesis, this test statistic follows a t-distribution with (n nap + n coffee - 2) degrees of freedom and the p-value is less than the significance level of 0.05,

To determine if there is sufficient evidence that taking a nap promotes faster reaction time than drinking coffee, we can perform a two-sample t-test assuming equal variances. The null hypothesis is that there is no difference in the mean reaction times between the nap and coffee groups, while the alternative hypothesis is that the mean reaction time for the nap group is less than the mean reaction time for the coffee group.

Let's assume that we have collected data on reaction times for both the nap and coffee groups, and have calculated their sample means ( X nap and X coffee) and sample standard deviations (snap and  s coffee). We can then calculate the pooled standard deviation using the formula:

[tex]Sp = sqrt(((nnap - 1) * snap^2 + (ncoffee - 1) * scoffe^2) / (nnap + ncoffee - 2))[/tex]

where n nap and n coffee are the sample sizes for the nap and coffee groups, respectively. We can then calculate the test statistic using the formula:

t = (X nap - X coffee) / (Sp * sqrt(1/nnap + 1/ncoffee))

Under the null hypothesis, this test statistic follows a t-distribution with (n nap + n coffee - 2) degrees of freedom. We can calculate the p-value for this test statistic using a t-distribution table or a calculator. Alternatively, we can use Python or R to perform the test and calculate the p-value.

If the p-value is less than the significance level of 0.05, we can reject the null hypothesis and conclude that there is sufficient evidence that taking a nap promotes faster reaction time than drinking coffee. Otherwise, we fail to reject the null hypothesis.

After calculating the appropriate test statistic, we would save it into variable p2.C.Stat, rounding the value to two decimal places. We would then calculate the p-value for this test statistic and save it into variable p2.C.P, rounding the value to three decimal places.

It's important to note that the assumptions of the two-sample t-test, such as normality and equal variances, should be checked before performing the test. If these assumptions are not met, alternative tests such as the Wilcoxon rank-sum test may be more appropriate.

To know more about degrees of freedom click here:

brainly.com/question/16254305

#SPJ4

Answer:

The information that suits the display on a double-line graph is:Option: B and Option: C

B. number of Democrats and Republicans in the Senate during the past decade.

C. monthly sales of two different types of cars during a one-year period.

Step-by-step explanation:

A double-line graph consist of two axes.

It shows the occurrence and the categories  which are being compared over the time. i.e. it is used to compare two sets of the data.

Hence, the correct option is:

B. number of Democrats and Republicans in the Senate during the past decade.

C. Monthly sales of two different types of cars during a one-year period.

( C. Since the x-axis represent the number of months and the y-axis represent the number of cars sold.

B. Since, the decade are represented by the x-axis and the number of people are represented by y-axis )

whereas in option A the height and weight are represented by a different units.

Step-by-step explanation:

To indicate values in a data set that are above or below the average monthly order totals use AVG([Order Total]). Thus, option (D) is correct.

AVG([Order Total]): This expression calculates the average of the "Order Total" values in your data set. The average is simply the sum of all the order totals divided by the number of data points.

SUM([Order Total]) calculates the total sum of all order totals.

AVG([Order Total]) then divides that sum by the number of data points to find the average.

Now, to determine which values are above or below the average monthly order totals:

Thus, option (D) is correct.

Learn more about Excel here:

https://brainly.com/question/33738057

#SPJ12

The question attached here seems to be incomplete, the complete question is:

Which calculation would you use to indicate values in a data set that are above or below the average monthly order totals?

Select an answer:

AVG(SUM [Order Total])

SUM({Order Total])

SUM(AVG [Order Total])

AVG([Order Total]

Using Geometric Mean Theorem, In the given triangle, The length of altitude is 12.

The geometric mean theorem states that in a right triangle, the length of the altitude from the right angle to the hypotenuse is the geometric mean of the lengths of the two segments of the hypotenuse

In other words, the square of the length of the altitude from the right angle to the hypotenuse is equal to the product of the lengths of the two segments of the hypotenuse. And the length of the altitude itself is equal to the square root of this product.

Now,

As we know

using Geometric Mean Theorem,

hypotenuse=18+8=26

let base=a

then   26/a=a/8

a²=208

Now, using Pythagoras theorem

8²+(x+9)²=a²

(x+9)²=208-64

x+9=√144

x+9=12

Hence, The length of altitude is 12.

To know more about Geometric Mean Theorem visit the link

https://brainly.com/question/26257841

#SPJ1

The distance of road is 12 kilometres

Ratio is  shows how many times one number contains another. It is also the comparison of two quantities of the same units that indicates how much of one quantity is present in the other quantity

How to determine this

When total distance = 20 kilometres

The ratio of road distance to footpath distance = 3:2

So, the total ratio = 3+2 = 5

To determine the work out of road distance

Let x represent the work out of the road distance

x =3/5 * 20

x = 60/5

x = 12 kilometres

Therefore, the distance of road is 12 kilometres

Read more about Ratio

https://brainly.com/question/29754679

#SPJ1

The expression (a⁰) × (1/0²) when evaluated has an undefined value

The expression (a^0) × (1/0²) involves two operations: exponentiation and multiplication.

Firstly, any number raised to the power of 0 is equal to 1. Therefore, a^0 is equal to 1, no matter what the value of "a" is.

Next, the expression 1/0² involves division by 0, which is undefined. Division by 0 is undefined in mathematics because it leads to inconsistencies

Therefore, the value of the entire expression is undefined or "not a number" (NaN), since the second term involves division by 0.

In summary, the expression (a^0) × (1/0²) is undefined and cannot be evaluated.

Read more about expression at

https://brainly.com/question/15775046

#SPJ1

Score of 62.816 is the lowest score that can be earned in the California Police Officer Standards and Training test to be eligible to be hired by the agency.

We have a normal distribution of scores for the california peace officer standards and training Let X be the random variable representing scores for the California Police Officer Standards and Training test, X ~ Normal(50, 10²).

Mean = 50

Standard deviations = 10

Let x be the lowest score that can be earned to be eligible to be hired by the agency that is x is the lowest score than can be earned to get in top 10%. Therefore, P(X > x) = 0.10

P((X- 50)/10 > (x- 50)/10) = 0.10 (converting Normal variate to Standard Normal variate)

P(Z > (x - 50)/10) = 0.10 --(1)

From the Standard Normal Distribution table, P(Z > 1.2816) = 0.10 -- (2)

From comparing the equation (1) and (2),

=> (x- 50)/10 = 1.2816

=> x-50 = 12.816

=> x = 62.816

Thus, the required lowest score is 62.816.

For more information about normal distribution, refer:

https://brainly.com/question/4079902

#SPJ4