Practice Test Discussion

A class is divided into two sections A and B. Passing average of 20 students of section A is 80% and passing average of 30 students of section B is 70%. What is the passing average of both the sections?

74%

72%

75%

77%

None of these

Explanation

Given,

$n_{1} = 20, n_{2} = 30, a_{1} = 80 %, a_{2} = 70 %$

We know the formula

Weighted average(Aw)= $= \frac{n_{1} a_{1} + n_{2} a_{2}}{n_{1} + n_{2}}$

∴ Total average

$= \frac{20 \times 80 + 30 \times 70}{20 + 30} = \frac{1600 + 1200}{50} = 74 %$

Hence, Option A is correct.

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