• Numerical Ability - Average
Question

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

  • A) 100
  • B) 110
  • C) 120
  • D) 150
  • E) 115
Solution

Ans.(a)
Sol. Suppose the number of candidates passed = x
∴ 39x + 15 (120 - x) = 120 × 35
⇒ 24x = 120 × 35 - 120 × 15
= 120 (35 - 15) = 120 × 20
⇒ x = 100

Ans.(a)
Sol. Suppose the number of candidates passed = x
∴ 39x + 15 (120 - x) = 120 × 35
⇒ 24x = 120 × 35 - 120 × 15
= 120 (35 - 15) = 120 × 20
⇒ x = 100
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