The mean of five numbers is 18. If one number is excluded, their mean is 16. The excluded number is:
Explanation:
Let the number excluded be 'x'
Sum of the 5 numbers = 5 × 18 = 90
Sum of remaining 4 numbers = 90 - x = 4 × 16
⇒ x = 90 - 64 = 26
Alternately, Had the excluded number been 18, the average of the remaining numbers wouldn't have changed.
Since the average of remaining 4 numbers decreased by 2, it means the excluded number is 4 × 2 = 8 more than the original average.
∴ Excluded number = 18 + 8 = 26.
Hence, option (c).
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