Foundation Mathematics Primary 5 Average

Four friends measured their heights at the Tampines Recreation Centre. The average height of the four friends is 144 cm. Three of them are 140 cm, 148 cm and 152 cm tall. What is the height of the fourth friend?

A 136 cm
B 148 cm
C 140 cm
D 144 cm
Show Worked Solution

Worked Solution

Step 1: Use the relationship Total = Average × Number of data values. Total height of 4 friends = 144 × 4 = 576 cm Step 2: Find the sum of the three known heights. 140 + 148 + 152 = 288 + 152 = 440 cm Step 3: Subtract to find the fourth friend's height. Fourth friend's height = 576 − 440 = 136 cm Answer: 136 cm

Correct answer: 136 cm

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