Question

Mean marks obtained by a student in his five subjects are $15$. In English he secures $8$ marks, in Economics $12$, in Mathematics $18$, and in Commerce $9$. Find out the marks he secured in Statistics.

Answer 1

Given:
Mean marks of five subjects $=\overline{x}=28$
Marks in English $=8$
Marks in Economics $=12$
Marks in Mathematics $=18$
Marks in Commerce $=9$
To find: Marks in Statistics
Let marks scored in statistics be $S$
Substituting the given values in the formula for mean

$\overline{x}=\frac{\text{sum of terms}}{\text{total number of terms}}$

$15=\frac{S+8+12+18+9}{5}$
$15\times 5=S+47$
$75-47=S$
$\therefore S=28$
Hence, marks scored in statistics is $28$