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

14

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15

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16

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17

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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 are 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=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.