Question

Mean of 20 observations (numbers) is 30. If one number is excluded, the mean of remaining numbers becomes 28. The excluded number is ______.

Options

• 532

• 1132

• 68

• 572

Answer 1

Mean of 20 observations (numbers) is 30. If one number is excluded, the mean of remaining numbers becomes 28. The excluded number is 68.

Explanation:

The sum of the original 20 observations is 20 × 30 = 600. After excluding one number, the remaining 19 observations have a mean of 28, resulting in a sum of 19 × 28 = 532, meaning the excluded number is 600 − 532 = 68.