Question

15. The average weight of 9 boys in a class is
42 kg. Another boy joined the class and the
new average was found to be 42.5 kg. Find
the weight of the new boys.​

Answer 1

Step-by-step explanation:

Mean=sum of numbers /number of items

42=sum if weights /9

Sum of their weights =42x9 =378

New sum of wights = 42.5x10 = 425

Weight of new boy = difference between the two sums

425-378= 47kg