The average weight of A, B and C is 45 kg. If the average weight of A and B be 40 kg and that of B and C be 43 kg, then the weight of B is:
Show answer & explanation
Correct answer: A
Explanation
The correct option is 1.
average weight of A, B and C is 45 kg
= 45
A + B + C = 45 × 3 = 135
the average weight of A and B is 40 kg
= 40
A + B = 40 × 2 = 80
the average weight of B and C is 43 kg
= 43
B + C = 43 × 2 = 86
adding A + B + B + C = 80 + 86 = 166
subtracting A + B + C from this we get
166 - 135 = 31
B = 31kg