NCHMCT JEE 2021 Question Paper with solutions for online practice

Question : 82 of 200

Marks: +1, -0

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

\;{1}/{2} {kg}

. The weight of the new student is

Solution:

Let the average be

x

.
Then, sum of weights of all 50 students

=50 x

According to the question,

50 x-50+y=50(x+\;{1}/{2})

Where

y

is the weight of new student.

\;⇒ 50 x-50+y \;\; =50 x+25

⇒ \;\; -50+y \;\; =25

⇒ y \;\; =75 {kg}

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