2016 · Q92
In a class of 100 students, there are 70 boys whose average marks in a subject are 75. If the average marks of the complete class is 72, then what is the average marks of the girls ?
Elementary MathematicsStatistics
- A64
- B65
- C68
- D74
Explanation
The class total is 100×72 = 7200 marks, of which the 70 boys contribute 70×75 = 5250. The 30 girls therefore total 1950, averaging 65 — not 64 as the stored key claimed. The stored key A is corrected to option B.