Multiple choice

The average number of marks scored by a person in subjects A, B and C was 82. The ratio of marks scored by him in subjects A and B was 3 : 4 and in subjects B and C was 3 : 5, respectively. Find the difference between the marks scored by him in subjects B and C.

  1. 36

  2. 42

  3. 48

  4. 54

  5. 60
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C Correct answer
Explanation

Given A:B = 3:4 and B:C = 3:5, we find the combined ratio A:B:C = 9:12:20. The sum of parts is 41. Average of 82 means total marks = 246. Each part is 246 / 41 = 6. Marks for B = 12 * 6 = 72, marks for C = 20 * 6 = 120. Difference = 120 - 72 = 48.

AI explanation

The total marks for the three subjects is 3 times 82, which equals 246. The combined ratio of marks in subjects A, B and C is 9 : 12 : 20, making the sum of the ratio parts 41. The value of one ratio part is 246 divided by 41, which equals 6. The marks for subject B are 12 times 6 (72) and for subject C are 20 times 6 (120), so the difference is 120 minus 72, which equals 48.

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