Comparing Measures of Center and Variability — Quiz
Question 5 • Grade 7 Mathematics
Two months ago, the mean daily rainfall in a local city was 9 point 4 cm. The mean absolute deviation was 3 point 5 cm. Last month, the mean daily rainfall in that city was 11 point 5 cm, and the mean absolute deviation was 1 point 6 cm. Which statement about the rainfall is true?
Answer
A
Last month, the amount of rain that fell each day varied less than the month before.
B
Last month, the amount of rain that fell each day varied about the same as the month before.
C
More rain fell two months ago than last month.
D
About the same amount of rain fell two months ago as last month.
Explanation
The mean absolute deviation measures how much the daily rainfall amounts typically differ from the mean. Last month’s MAD was 1.6 cm, lower than the 3.5 cm MAD two months ago, so daily rainfall varied less last month. The mean rainfall was also higher last month (11.5 cm compared with 9.4 cm), but that does not change the conclusion about variation.
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