Solved UPSC CDS/OTA Question
A solved UPSC CDS/OTA PYQ — decoded step-by-step.
Solve it the standard way once — then learn the shortcut.
The average weight of 4 men A, B, C and D is 67 kg. The 5th man E is included and the average weight decreases by 2 kg. A is replaced by F. The weight of F is 4 kg more than E. Average weight decreases because of the replacement of A and now the average weight is 64 kg. Find the weight of (a)
Step-by-Step Solution
The complete worked solution.
Every step explained — no skipped algebra.
Sum of the weights of A, B, C and D
= 67 × 4 = 268 kg and average weight of A, B, C, D and E = 67 – 2 = 65 kg
∴ Sum of the weights of A, B, C, D and E =
65 × 5 = 325 kg
∴ Weight of E = 325 – 268 = 57 kg
∴ Weight of F = 57 + 4 = 61 kg
Now, average weight of F, B, C, D and E = 64 kg
∴ Sum of the weights of F, B, C, D and E = 64 × 5 = 320 kg
∴ Sum of the weights of B, C and D
= 320 – 57 – 61 = 202 kg
∴ Weight of A = 268 – 202 = 66 kg