Question

A school has four sections of chemistry in class XII having $40,35,45$ and $42$ students. The mean marks obtained in Chemistry test are $50,60,55$ and $45$ respectively for the four sections. The overall average of marks per students is -

• A. $53$
• B. $43$
• C. $55.3$
• D. $52.25$

Answer 1

The correct option is D $52.25$

$\Rightarrow$ For $1st$ section total marks obtain by class $=40\times 50=2000$

$\Rightarrow$ For $2nd$ section total marks obtain by class $=35\times 60=2100$

$\Rightarrow$ For $3rd$ section total marks obtain by class $=45\times 55=2475$

$\Rightarrow$ For $4th$ section total marks obtain by class $=42\times 45=1890$

$\Rightarrow$ The overall average of marks per students $=\frac{2000+2100+2475+1890}{40+35+45+42}$

$=\frac{8465}{162}$

$=52.25$