The average weight of the students

Gian,

My 2 cents.

let n be the number of students in the class. We are asked to solve for n.

Let w1, w2, w3......wn respectively be the weight of individual students upto n

so we know that

n * 48 = w1 + w2 + w3 + w4 .....+ wn

Option A:

Let w1 = 46 & w2= 54, this weight was changed to w1=64 & w2 = 45 and avg is 50.

so

n * 48 = 46 + 54 + w3 + w4+....wn ----- equation 1

n * 50 = 64 + 45 + w3+ w4.......wn ------- equation 2

Now subtract eq 1 from eq2

50n - 48n = 64+45+w3+...wn - ( 46+54+w3.....wn)

2n = 9

n= 4.5 students, As wWe were able to solve for N. So lets think option A is correct

Option B:

2 more students 44 & 52 were added and avg remained the same.

if you average (44+52)/2 == the avg is 48....

so it doesn't matter if n is 50 or 100 or 2 etc.....

so we cant solve for n.


In all I think this is a poor question because students cannot be in decimals. i.e. in A, we solved for n = 4.5

This was my understanding of the problem. Hope it helped if my explanation is correct.