### 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.)

A. 55 kg

B. 57 kg

C. 66 kg

D. 56 kg

According to the question, Total increase in weight including teacher $\begin{array}{l}\text{= 400 × 35}\\ \text{= 14000 gm}\\ \text{= 14 kg}\end{array}$ If the teacher’s weight has been ’42’ kg so there would have not been any change in average weight. $\begin{array}{l}\text{∴ Teacher’s weight }\\ =42+14\\ =56\ \text{kg}\end{array}$