Paper 2 · November 2019 · Descriptive Statistics

In a survey of 100 athletes at a marathon, the amount of water taken, in litres, was recorded as: 0-0.5 litres by 8 athletes, 0.5-1.0 litres by 20 athletes, 1.0-1.5 litres by 29 athletes, 1.5-2.0 litres by 22 athletes, and 2.0-2.5 litres by 21 athletes. Using the midpoint of each class, what is the estimated mean amount of water taken, in litres?

A1.30

B1.35

C1.39

D1.45

Explanation

Using midpoints 0.25, 0.75, 1.25, 1.75, 2.25: mean

= \frac{8(0.25)+20(0.75)+29(1.25)+22(1.75)+21(2.25)}{100} = \frac{139}{100} = 1.39

litres.

Derived from ZIMSEC Statistics Paper 2, November 2019, Q2

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