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

Answer: Option D

According to the question,
Total increase in weight including teacher
= 400 × 35
= 14000 gm
= 14 kg
If the teacher's weight has been '42' kg so there would have not been any change in average weight.
∴ Teacher's weight = 42 + 14 = 56 kg.