Question

The average weight of a and b is 47.5kg. The average weight of b and c is 52.5kg.The average weight of all 3 of them is 50 kg.Find the average weight of a and c.

Answer 1

Average weight of a and b is
$\frac{(a + b)}{2} = 47.5$
so (a+b)=95 ---> [1]

Average weight of b and c is
$\frac{(b + c)}{2} = 52.5$
so b+c=105--->[2]

Average weight of a and b and c is
$\frac{(a + b + c)}{3} = 50$
so a+b+c= 150--->[3]

By [3]-[1]

a+b+c-a-b=150-95

c=55

By [3]-[2]

a+b+c-b-c=150-105

a=45

So average of a and c is given by
$\frac{a + c}{2}$
$\frac{45 + 55}{2} = 50$
So average a and c is 50