Statisticshard · Past Paper
The mean of five numbers is 20. If one number is excluded, the mean becomes 15. What is the excluded number?
A20
B35
C40
D50
✓ Correct Answer: C — 40
Sum of 5 numbers = 5 * 20 = 100. Sum of 4 numbers = 4 * 15 = 60. Excluded number = 100 - 60 = 40.
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