Question

two months ago, the mean daily rainfall in a local city was 9.4 cm. the mean absolute deviation was 3.5 cm. last month the mean daily rainfall in that city was 11.5 cm, and the mean absolute deviation was 1.6 cm. which statement about the rainfall is true? more rain fell two months ago than last month. about the same amount of rain fell two months ago as last month. last month, the amount of rain that fell each day varied about the same as the month before. last month, the amount of rain that fell each day varied less than the month before.

Explanation:

Step1: Analyze the first two options

Mean daily rainfall two months ago was \(9.4\) cm and last month was \(11.5\) cm. Since \(11.5>9.4\), options “More rain fell two months ago than last month” and “About the same amount of rain fell two months ago as last month” are incorrect.

Step2: Analyze the last two options

Mean absolute deviation (MAD) measures the variability. Two months ago, MAD was \(3.5\) cm and last month it was \(1.6\) cm. Since \(1.6 < 3.5\), the amount of rain that fell each day varied less last month.

Answer:

Last month, the amount of rain that fell each day varied less than the month before.