Multiple choice

In a park there are 120 marbles in which red, blue and green marbles are in the ratio 5 : 4 : 3. The average weight of the blue marbles is 30 grams, that of the red marbles is 60 grams and that of the green marbles is half that of the blue marbles. Find the mean weight of all the marbles.

  1. 38.75 grams

  2. 39.75 grams

  3. 40.75 grams

  4. 41.75 grams

  5. Na
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A Correct answer
Explanation

Total marbles = 120. Ratio 5:4:3 means 50 red, 40 blue, 30 green. Weights: Blue = 30g, Red = 60g, Green = 15g (half of blue). Total weight = (50 * 60) + (40 * 30) + (30 * 15) = 3000 + 1200 + 450 = 4650. Mean weight = 4650 / 120 = 38.75g.

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