Mean of twenty observations is 15. If two observations 3 and 14 replaced by 8 and 9 respectively, then the new mean will be

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Solution

The correct option is B 15
Mean of 20 observations = 15
$∴$ Sum of 20 observations = $15 \times 20 = 300$
Replacing 3 and 14 by 8 and
9 will mean that 3 + 14= 17 is replaced by 8 + 9 = 17.
Hence there will be no effect on the sum. It will still remain 300, so the mean will not change and will remain 15.

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Mean of twenty observations is 15. If two observations 3 and 14 replaced by 8 and 9 respectively, then the new mean will be

The correct option is B 15Mean of 20 observations = 15∴ Sum of 20 observations = 15×20=300Replacing 3 and 14 by 8 and 9 will mean that 3 + 14= 17 is replaced by 8 + 9 = 17.Hence there will be no effect on the sum. It will still remain 300, so the mean will not change and will remain 15.