2026 · Q39
The sum of the deviations of a set of n numbers x1, x2, x3, ..., xn measured from 15 is -90 and the sum of the deviations of the same numbers measured from -3 is 54. What is the arithmetic mean?
Elementary MathematicsStatistics
- A3.25
- B3.50
- C3.75
- D4.25
Explanation
Let the sum of the numbers be S: S−15n=−90 and S+3n=54. Subtracting eliminates S: 18n=144, so n=8, and then S=54−24=30. The mean is 30/8=3.75, option C.