The average weight of A, B and C is 40 kgs. Weight of C is 24 kgs more than A’s weight and 3 kgs less than B’s weight. What will be the average weight of A, B, C and D, if D weights 15 kgs less than C?
Correct Answer: 38 kgs
Average weight of A, B and C = 40 kgs
Total weights of A , B and C = 40 × 3 = 120 kgs
Weight of C = (A + 24) and C = (B - 3)
∴ A + 24 = B - 3
⇒ B = A + 27
Now A + B + C = 120
⇒ A + A + 27 + A + 24 = 120
⇒ 3A + 51 = 120
⇒ A = $$\frac{69}{3}$$ = 23 kg
B = A + 27 = 23 + 27 = 50 kg
C = 120 - 23 - 50 = 47 kg
D = 47 - 15 = 32 kg
∴ Required average weight of A, B, C and D
= $$\frac{23 + 50 + 47 + 32}{4}$$
= $$\frac{152}{4}$$
= 38 kg
Total weights of A , B and C = 40 × 3 = 120 kgs
Weight of C = (A + 24) and C = (B - 3)
∴ A + 24 = B - 3
⇒ B = A + 27
Now A + B + C = 120
⇒ A + A + 27 + A + 24 = 120
⇒ 3A + 51 = 120
⇒ A = $$\frac{69}{3}$$ = 23 kg
B = A + 27 = 23 + 27 = 50 kg
C = 120 - 23 - 50 = 47 kg
D = 47 - 15 = 32 kg
∴ Required average weight of A, B, C and D
= $$\frac{23 + 50 + 47 + 32}{4}$$
= $$\frac{152}{4}$$
= 38 kg