Basic Statistics Flashcards
6 cards from real Civil Service Numerical Reasoning Test practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Basic Statistics flashcards as text
A data set has mean 25, and five values. Their sum must be:
Answer: 125
Mean = sum ÷ count. Sum = mean × count = 25 × 5 = 125.
A class of 30 students has a mean test score of 64. What is the total of all scores?
Answer: 1,920
Total = mean × number of students = 64 × 30 = 1,920.
Values: 10, 20, 30, 40, 50. If 20 is removed, what happens to the mean?
Answer: The mean increases
Original mean = 150 ÷ 5 = 30. New set: 10, 30, 40, 50. New mean = 130 ÷ 4 = 32.5. Removing a below-average value raises the mean.
Values: 5, 10, 15, 20, 25. What is the mean?
Answer: 15
Sum = 75. Mean = 75 ÷ 5 = 15.
Seven values: 6, 6, 8, 10, 12, 14, 16. What is the median?
Answer: 10
The values are already ordered. Middle (4th of 7) value = 10.
A set of 4 values has a mean of 12. Three of the values are 9, 14, and 11. What is the fourth value?
Answer: 14
Total = 12 × 4 = 48. Sum of known values = 9 + 14 + 11 = 34. Fourth value = 48 − 34 = 14.