Question

The rainfall (in mm) in a city on 7 days of a certain week was recorded as follows:

Day	Mon	Tue	Wed	Thu	Fri	Sat	Sun
Rainfall (in mm)	0.0	12.2	2.1	0.0	20.5	5.3	1.0

(i) Find the range of the rainfall from the above data.
(ii) Find the mean rainfall for the week.
(iii) On how many days was the rainfall less than the mean rainfall.

Answer 1

(i) The range of the rainfall = Maximum rainfall - Minimum rainfall

= 20.5 - 0.0

= 20.5 mm .

(ii) The mean rainfall = $\frac{(0.0+12.2+2.1+0.0+20.5+5.3+1.0)}{7}=\frac{41.1}{7}=5.87\mathrm{mm}$.

(iii) Clearly, there are 5 days (Mon, Wed, Thu, Sat, and Sun), when the rainfall was less than the mean, i.e., 5.87 mm.