Advanced Mathematics Primary 6 Average

The average mass of 9 boys is 42 kg. When the heaviest boy left the group, the average mass of the remaining 8 boys was 40 kg. Find the mass of the boy who left.

A 50 kg
B 58 kg
C 62 kg
D 82 kg
Show Worked Solution

Worked Solution

Step 1: Total mass of 9 boys = 9 × 42 = 378 kg. Step 2: Total mass of remaining 8 boys = 8 × 40 = 320 kg. Step 3: Mass of the boy who left = 378 − 320 = 58 kg. Answer: 58 kg

Correct answer: 58 kg

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