Question

The mean weight of 34 students of a school is 42 kg. If the weight of the
teacher is included, then the mean rises by 400 g. Find the weight (in kg) of the teacher.

• A. 66
• B. 56
• C. 55
• D. 57
• E. None of these

Answer 1

The correct option is B 56

Here, mean weight of 34 students = 42
Total weight of 34 students = 34 $\times$ 42
= 1428 kg
Weight of teacher = 35 $\times$ 42.4 - 1428
= 1484 - 1428
= 56 kg
Alternate Method
Weight of the teacher
= 42 (34 + 1) $\times$ 0.4
= 42 + 35 $\times$ 0.4
= 42 +14
= 56 kg