Question 1

Which of the following best describes the 90th percentile in a data set?

Accepted Answer

It is the value below which 90% of the data falls.

Question 2

In a class of 100 students, if your exam score is at the 80th percentile, what does this mean?

Accepted Answer

80 students scored lower than you.

Question 3

Which of the following statements about quartiles is TRUE?

Accepted Answer

Q2 is always equal to the median of the data set.

Question 4

Given the data set: 3, 5, 7, 9, 11, 13, 15, what is the median (Q2)?

Accepted Answer

$$9$$

Question 5

A data set has the following values: 4, 6, 8, 10, 12, 14. What is the first quartile (Q1)?

Accepted Answer

$$6$$

Question 6

Which of the following is NOT included in the five-number summary?

Accepted Answer

The mean

Question 7

For the data set: 1, 2, 3, 4, 5, 6, 7, 8, what is the five-number summary?

Accepted Answer

$$1, 2.5, 4.5, 6.5, 8$$

Question 8

If a data set has an odd number of values, what is the correct procedure for finding quartiles?

Accepted Answer

Repeat the median and then split the data into two equal halves.

Question 9

A hospital records the weights of patients of a certain height. If a patient’s weight is at the 90th percentile, what does this indicate?

Accepted Answer

90% of patients of that height weigh less than this patient.

Question 10

Given the data set: 2, 4, 6, 8, 10, 12, 14, 16, what is the third quartile (Q3)?

Accepted Answer

$$12$$

Question 11

Which interpretation is correct for Q1 in a data set?

Accepted Answer

25% of the data values are less than or equal to Q1.

Question 12

A data set has minimum value 5, Q1 = 10, median = 15, Q3 = 20, and maximum value 25. Which value represents the 75th percentile?

Accepted Answer

$$20$$

Question 13

If the ages of children in a daycare are: 2, 5, 7, 7, 8, 8, 8, 12, what percentage of children are younger than the first quartile (Q1)?

Accepted Answer

25%

Question 14

Which of the following is the correct order for the five-number summary?

Accepted Answer

Minimum, Q1, Median, Q3, Maximum

Question 15

For the data set: 0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 28, what is the five-number summary?

Accepted Answer

$$0, 0, 1, 2, 28$$

Question 16

Which of the following statements about percentiles is FALSE?

Accepted Answer

The 90th percentile always means a score of 90%.

Question 17

A data set is sorted in ascending order. What is the first step in finding the quartiles?

Accepted Answer

Find the median (Q2) of the data set.

Question 18

If a data set has an even number of values, how are the lower and upper halves determined for quartile calculation?

Accepted Answer

Split the data into two equal halves, excluding the median.

Question 19

Which of the following best explains why the five-number summary is useful?

Accepted Answer

It provides information about the spread and center of the data, including extremes and quartiles.

Percentiles, Quartiles, and the Five-Number Summary

Study Guide - Practice Questions