question_answer

There are 50 students in a class. One of them weighing 50 kg goes away and a new student joins. By this the average weight of the class increases by \[\frac{1}{2}\,kg.\] The weight of the new student is

A) 70 kg                

B) 72 kg

C) 75 kg

D) 76 kg

Correct Answer: C

Solution :

Let the average be x.

Then, sum of weights of all 50 students = 50x

According to the question,

\[50x-50+y=50\left( x+\frac{1}{2} \right)\]

Where y is the weight of new student.

\[50x-50+y=50x+25\]

\[-\,50+y=25\]\[\Rightarrow \]\[y=75\text{ }kg\]