Average weight of a group of 20 ,boys was calculated to be 89.4, kg and it was later discovered that

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The average weight of a group of $20 \,boys$ was calculated to be $89.4\, kg$ and it was later discovered that one weight was misread as $78 \,kg$ instead of $87 \,kg.$ The correct average weight is (in $kg.$)

A

$88.95$

B

$89.25$

C

$89.55$

D

$89.85$

Solution

Sum of the weight of $20$ boys $=89.4 \times 20=1788 \,kg$

According to the question.

New Average $=1788-78+87=\frac{1797}{20}=89.85\, kg$

Standard 13

Quantitative Aptitude

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