Advanced Mathematics Primary 5 Average

The average mass of 3 boys is 42 kg. If a 4th boy with a mass of 50 kg joins them, what is the new average mass of the 4 boys?

A 44 kg
B 46 kg
C 42 kg
D 48 kg
Show Worked Solution

Worked Solution

Find the total mass of the 3 boys: 3 × 42 kg = 126 kg. Add the mass of the 4th boy to find the new total mass: 126 kg + 50 kg = 176 kg. The new number of boys is 4. New average mass = Total mass ÷ Number of boys New average mass = 176 kg ÷ 4 = 44 kg. Key formula: Total Value = Average × Number of Data; New Average = New Total Value ÷ New Number of Data Answer: 44 kg

Correct answer: 44 kg

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