The average mark obtained by 120 candidates in a certain examination is 40. If the average marks of passed candidates are 45 and that of the failed candidates is 20, then what is the number of candidates who passed in the examination?
According to question, => 45 × x + 20 × (120 − x) = 120 × 40 => 45x + 2400 – 20x = 4800 => x = 96