The average weight of A, B, C is 40 kg, the average weight of B, D, E is 42 kg and the weight of F is equal to that of B. What is the average weight of A, B, C, D, E and F?
- (a) 40·5 kg
- (b) 40·8 kg
- (c) 41 kg ✓ UPSC's answer
- (d) Cannot be determined as data is inadequate
Why the answer is (c)
• The sum of the weights of A, B, and C is 3 × 40 = 120 kg.
• The sum of the weights of B, D, and E is 3 × 42 = 126 kg.
• Adding these two sums gives A + 2B + C + D + E = 120 + 126 = 246 kg.
• Since the weight of F is equal to the weight of B, the total weight of A, B, C, D, E, and F is A + B + C + D + E + F = (A + 2B + C + D + E) = 246 kg.
• The average weight of the six persons is 246 / 6 = 41 kg.
• Therefore, the correct option is (c).
Why the other options are wrong
- (a) 40·5 kg
- 40.5 kg is incorrect because the total weight is 246 kg, not 243 kg.
- (b) 40·8 kg
- 40.8 kg is incorrect because the total weight is 246 kg, not 244.8 kg.
- (d) Cannot be determined as data is inadequate
- The data is adequate because the weight of F is explicitly linked to B, allowing the total sum to be calculated.
Asked in the CSAT Paper II of the UPSC Civil Services Preliminary Examination 2022, held on 5 June 2022. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.