Question

The average of marks obtained in 120 students was 35. If average of passed candidates was 39 and that of failed candidates is 15, the numbers of candidates who passed the examinations is

• A. 100
• B. 110
• C. 120
• D. 80
• E. None of these

Answer 1

The correct option is A 100

Here, total marks obtained by 120 students = 120 $\times$ 35 = 4200
Let the number of passed candidates =
Then, total marks obtained by passed candidates = x $\times$ 39
And, total marks obtained by failed candidates = (120 - x) $\times$ 15
Again, 39x + (120 - x) $\times$ 15 = 4200
$\Rightarrow$39x + 1800 - 15x = 4200
$\Rightarrow$ 24x = 2400
$\therefore x=\frac{2400}{24}=100$