Practice Test Discussion

The average marks obtained by 8 students in a certain examination is 51. The average marks obtained by another 9 students is 68. What will be the average marks obtained by all the students?

60.5

59.5

None of these

Explanation

Given,

$n_{1} = 8, a_{1} = 51, n_{2} = 9, a_{2} = 68$

According to the formula

Required average = $\frac{n_{1} a_{1} + n_{2} a_{2}}{n_{1} + n_{2}}$

$= \frac{8 \times 51 + 9 \times 68}{8 + 9} = \frac{408 + 612}{17} = \frac{1020}{17}$

=60

Hence, Option A is correct.

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