Advanced Mathematics Primary 6 Average

At a NTUC FairPrice warehouse, the mean weight of 6 boxes is 8.5 kg. When the heaviest box is removed, the mean weight of the 5 remaining boxes drops to 7 kg. What is the weight of the heaviest box?

A 1.5 kg
B 9 kg
C 16 kg
D 35 kg
Show Worked Solution

Worked Solution

Step 1: Convert the first mean back to a total. Total weight of all 6 boxes = mean × count = 8.5 × 6 = 51 kg. Step 2: Convert the second mean back to a total. After the heaviest box is removed, only 5 boxes remain. Total weight of the 5 remaining boxes = 7 × 5 = 35 kg. Step 3: The heaviest box accounts for the difference between the two totals. Heaviest box = 51 − 35 = 16 kg. Check: if we add the heaviest 16 kg back to the remaining 35 kg, we get 51 kg, and 51 ÷ 6 = 8.5 kg ✓. Final answer: 16 kg. Answer: 16 kg

Correct answer: 16 kg

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