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

(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.

Answers (1)

Given,

(i) Range = Maximum rainfall - Minimum rainfall

= 12.2 - 0.0

= 12.2

(ii)  We know, Arithmetic mean = \frac{sum\ of\ observations}{number\ of\ observation}

\\ = \frac{0.0+12.2+2.1+0.0+20.5+5.5+1.0}{7} \\ = \frac{41.3}{7} \\ \\ = 5.9

Therefore, mean rainfall is 5.9\ mm

(iii) Here, mean = 5.9\ mm

Mon(0.0), Wed(2.1), Thu(0.0), Sat(5.5), Sun(1.0) are less than the mean

Therefore, on 5 days, rainfall was less than the mean.

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