Numerical Ability Reviewer Part 24 with Answers

Part 24 of our Numerical Ability reviewer has 20 practice questions in the style of the Civil Service Exam. Answer them in order, read the explanation after each one, and check your score against the 80% passing mark at the end. Questions and choices are reshuffled every time you retake the part.

Start Part 24

Sample questions from Part 24

Here are a few questions from this part. Take the full test to answer all 20 and get your score.

Sample question 1

The mean of 8 numbers is 25. Two more numbers are added, and the mean of all 10 numbers becomes 27. If one of the added numbers is 32, what is the other?

Answer: 38

Original sum = 8 × 25 = 200. New sum = 10 × 27 = 270. The two added numbers total 70, so the other is 70 − 32 = 38.

Sample question 2

What is the median of the numbers 12, 15, 9, 21, 18, 15, 30, 24?

18
17
16.5
15

Answer: 16.5

Arrange in order: 9, 12, 15, 15, 18, 21, 24, 30. With 8 values, the median is the mean of the 4th and 5th: (15 + 18) ÷ 2 = 16.5.

Sample question 3

The mean of five numbers is 18. If each number is multiplied by 3 and then 4 is subtracted from each, what is the new mean?

Answer: 50

Multiplying every value by 3 triples the mean (54); subtracting 4 from every value lowers it by 4: 54 − 4 = 50.

Sample question 4

Section A has 30 students with a mean score of 78, and Section B has 20 students with a mean score of 84. What is the mean score of all 50 students?

80.4
80
81
79.2

Answer: 80.4

Total = 30 × 78 + 20 × 84 = 2,340 + 1,680 = 4,020. Mean = 4,020 ÷ 50 = 80.4. (The simple average 81 ignores the group sizes.)

Sample question 5

Five whole numbers have a mean of 20, a median of 18, a mode of 15 and a range of 14. What is the second largest number?

Answer: 23

The mode 15 appears at least twice, so the smallest two are 15, 15 and the median (middle) is 18. Range 14 gives a largest value of 15 + 14 = 29. Sum = 5 × 20 = 100, so the fourth is 100 − (15 + 15 + 18 + 29) = 23.

Numerical Ability Reviewer - Part 24