Average of marks obtained by 120 candidates was 35. If average of marks of passed candidates was 39

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The average of marks obtained by $120$ candidates was $35.$ If the average of marks of passed candidates was $39$ and that of failed candidates was $15,$ the number of candidates who passed the examination is

A

$100$

B

$110$

C

$120$

D

$150$

Solution

Let, the number of candidates who passed $=x$

Then, $39 \times x+15 \times(120-x)=120 \times 35$

$\therefore \quad 24 x=4200-1800$

or, $x=\frac{2400}{24}$

$x=100$

Standard 13

Quantitative Aptitude

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