Question
The average of marks obtained by 50 candidates was 56.
If the average of the passed candidates was 60 and that of the failed candidates was 50, then the number of those candidates, who passed the examination was:Solution
Suppose the number of candidates passed = x ∴ 60x + 50 (50 - x) = 50 × 56 ⇒ 10x = 50 × 56 - 50 × 50 = 50 (56 - 50) = 50 × 6 ⇒ x = 30
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