There are two groups A and B of a class, consisting of 42 and 28 students, respectively. If average

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There are two groups $A$ and $B$ of a class, consisting of $42$ and $28$ students, respectively. If the average weight of group $A$ is $25 \,kg$ and that of group $B$ is $40 \,kg ,$ find the average weight of the whole class.

A

$69$

B

$31$

C

$70$

D

$30$

Solution

Required average weight $=\frac{42 \times 25+28 \times 40}{42+28}$

$=\frac{1050+1120}{70}=\frac{2170}{70}=31 \,kg$

Standard 13

Quantitative Aptitude

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