question_answer 8)

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

Day	Mon	Tue	Wed	Thurs	Fri	Sat	Sun
Rainfall (in mm)	0.0	12.2	2.1	0.0	20.5	5.5	1.0

(i) Find the range of the rainfall in 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:

                (i) Range of the rainfall = Highest rainfall ? Lowest rainfall \[=\text{2}0.\text{5 mm}-0.0\text{ mm}=\text{2}0.\text{5 mm}\] (ii) Mean rainfall for the week     \[\text{=}\frac{\text{sum of all observations}}{\text{number of observaion}}\] \[=\frac{0.0+12.2+2.1+0.0+20.5+5.5+1.0}{7}\]                                              \[=\frac{41.3}{7}=5.9\text{mm}\] (iii) The rainfall was less than the mean rainfall on 5 days.