Question

The average weight of a group of boys is 30 kg. After a boy of weight 35 kg joins the group, th
average weight of the group goes up by 1 kg. Find the number of boys in the group originally?
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Answer 1

Answer:

Let the no. of boys=X

total weight of X boys=30X

Total weight of (X+1) boys=(X+1)×31

31X+31=30X+35

X=4

Total no. of boys is 4