Average weight of 21 boys was recorded as 64 ,kg. If weight of teacher was added, average increased

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The average weight of $21$ boys was recorded as $64 \,kg.$ If the weight of the teacher was added, the average increased by one $kg.$ What was the teacher's weight?

A

$86$

B

$64$

C

$72$

D

$98$

Solution

Let the weight of teacher $=x kg$

According to the question $21 \times 64+x=22 \times 65$

$x=1430-1344 \Rightarrow x=86 kg$

Hence weight of the teacher is $86 \, kg.$

Standard 13

Quantitative Aptitude

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