# GRE Subject Test: Math : Probability & Statistics

## Example Questions

### Example Question #31 : Other Topics

What is the mean of: ?

Explanation:

Find the sum of all the numbers in the set:

Count how many numbers are in the set...

There are six numbers...

Divide the sum of the set by how many numbers to find the mean...

### Example Question #32 : Other Topics

What is the mean of

?

None

Explanation:

Find the sum of all the numbers in the set:

Count how many numbers are in the set...

There are  numbers..

To find the mean, divide the sum by how many numbers...

### Example Question #31 : Probability & Statistics

What is the mean of: ?

Explanation:

Step 1: To find the mean, we need to first find the sum of the numbers in the set.

Step 2: Count how many numbers are in the set...

There are  numbers in the set.

Step 3: To find the mean, divide the sum of the numbers in the set by how many numbers there are in the set...

### Example Question #32 : Probability & Statistics

The average test score was an , the scores were as followed , and . Find

Explanation:

Use the mean equation:

Enter in the numbers

Simplify

Multiply each side by

Subtract  from both sides

### Example Question #1 : Variance

Find the variance of the scores 18, 4, 9, 6, 11, and 20.

Explanation:

First find the mean of the scores by adding them up and dividing by the number of scores.

Subtract the mean of 11.33 from each of the scores.

Now, square the results.

Now we need the average of these values to get the variance. First, add up these values.

Now divide by 6 which is the number of scores.

Explanation:

or

### Example Question #31 : Statistics

What is the standard deviation of the numbers 3, 5, 8, 9, and 10?

Explanation:

The first step with standard deviation is to find the average or mean of the numbers. Add 3+5+8+9+10 together to get 35. Divide that by the number of scores, which is 5, to get a mean of 7.

Now, subtract the mean from each of the numbers

Next, square those values

Now find the mean of these squared differences by adding the values and then dividing by the amount of numbers, 5 in this case.

Finally, take the square root of this number to get the standard deviation.

### Example Question #1 : Range & Iqr

What is the range of the set of numbers: ?

Explanation:

Step 1: Arrange the numbers in the set from smallest to largest:

After we arrange, we get: .

Step 2: To find the range, subtract the largest number from the smallest number.

The range of the data set is .

### Example Question #1 : Range & Iqr

What is the range of the numbers:

Explanation:

Step 1: Re-write all numbers in order from smallest to largest

.

Step 2: Subtract the largest number and smallest number

The range is .

### Example Question #2 : Range & Iqr

What is the range of the set: {}

Explanation:

Step 1: Arrange the numbers from smallest to largest:

We get:

Step 2: Find the range.. To find this, subtract the biggest number from the smallest number

The range is