The average of 6 values is 12. A number is removed and the average decreases by 1. Find the number removed.
Explanation:
Let x be the value of number removed.
Given, (6 × 12 - x)/5 = 11
⇒ 72 - x = 55
⇒ x = 17.
Alternately,
Had the number removed been same as average (i.e. 12), the average of remaining 5 numbers would not have changed.
Since average of now 5 numbers decreases by 1 ⇒ the total decrease for remaining numbers = 5 × 1 = 5.
This means that the number removed was 5 more than the old average.
⇒ x = 12 + 5 = 17.
Hence, option (d).
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