Question

Find the average weight of 16 boys in a class of 50.25 kgs and that of the remaining 8 boys is 45.15 kgs. Find the average weight of all the boys in the class
A.47.55kgs
B.48 kgs
C.48.55 kgs
D.49.25 kgs

Answer 1

Hint: The average weight of 16 boys is given as 50.25 kgs and the average weight of 8 boys is given as 45.15 kgs. Using this we can find the total weight of the 16 boys and the 8 boys. Then we will add these weights to get the total weight of all the boys. Now, as we have to find the average weight of all the boys of class, we will divide the total weight by the total number of boys that will be 24.

Complete step-by-step answer:
Average weight of 16 boys in a class is 50.25 kgs. Thus, their total weight will be given by \[16 \times 50.25 = 804\] kgs. Now, we also know that the average weight of the remaining 8 boys is 45.15 kgs, so their total weight will be given by \[8 \times 45.15 = 361.2\] kgs.
Now, when we add both these weights will get the total weight of all the boys in the class. Thus, the total weight of all the boys will be given as \[804 + 361.2 = 1165.2\] kgs.
To find the average weight of all the boys in the class, we will divide the total weight of all the boys with the total number of boys. The total number of boys will be \[16 + 8 = 24\].
Thus, the average weight of all the boys in the class will be given as \[\dfrac{{1165.2}}{{24}} = 48.55\] kgs.
Hence, option (C) will be the correct option.

Note: A common mistake that many students may do is that they will take the average of the 2 average weights, which is incorrect, because that would mean there are 2 people with weights of 5.25 kgs and 45.15 kgs which is not true. We first have to find the total weights and then divide it by the total number of boys in the class.