Question

in a class there are 60 students .a student whose weight is 50 kg is left off and another student is newly admitted to the class. if there was an increase of 250gm in the average, weight of the newly admitted student is?

Answer 1

Solution:- In a class there are 60 students . A student whose weight is 50 kg is left off and another student is newly admitted to the class.

There was an increase of 250gm in the average, weight of the newly admitted student.

According to the question,

The average weight of 60 students was = 50 kg

When one student leaves the class the avg. increases by 250 gm.

∴Total weight increases due to 61 students = 61× 250 = 15,250 gm= 15. 250 kg

∴The weight of student who is the newly admitted student = 61 + 15.250 = 76.25 kg.

Now, A student whose weight is 50 kg is left off

= The average weight of 60 students - A student whose weight is 50 kg is left off

= 50 - 50

= 0.

[∴Answer:- 76.25 kg]

Answer 2

Let the average age of 60 students

=k kg

and the weight of the new student

=y kg

Total weight of 60 students

=60 k kg

$\frac{60k - 50 + y }{60} = k + \frac{1}{4}$

$(therefore \: 250g = \frac{1}{4} kg)$

$60 \: k - 50 + y = 60(k + \frac{1}{4} )$

$60 \: k - 50 + y = 60 \: k + 15$

$60 \: k - 60 \: k + y = 15 + 50$

$i.e .\: y = 65kg$

weight of newly admitted student

=65 kg