Multiple choice

Four persons A, B, C and D were checking their weights on a weighing machine. A's weight was 70 kg. C's weight was 30% less than D's weight. D's weight was 30 kg less than that of B. If the ratio of B's weight to that of C is 16 : 7, the average weight of A, B and C is

  1. 59.33 kg

  2. 61.36 kg

  3. 61.66 kg

  4. 62.33 kg

  5. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A = 70. D = B - 30. C = 0.7D = 0.7(B - 30). Ratio B/C = 16/7 implies B / (0.7(B - 30)) = 16/7. Solving for B: 7B = 11.2(B - 30) => 7B = 11.2B - 336 => 4.2B = 336 => B = 80. Then D = 50, C = 35. Average of A, B, C = (70 + 80 + 35) / 3 = 185 / 3 = 61.66.

AI explanation

Let the weights of B and C be 16x and 7x respectively. Since D is 30 kg less than B, the weight of D is 16x minus 30. Because C is 30% less than D, the weight of C is 0.7 multiplied by D, so 7x equals 0.7 multiplied by (16x minus 30). Solving this equation gives 7x equals 11.2x minus 21, meaning 4.2x equals 21 and x equals 5. The weights of A, B, and C are 70 kg, 80 kg, and 35 kg respectively, making their average (70 plus 80 plus 35) divided by 3, which equals 61.66 kg.

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