Question

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

$\begin{array}{cccccccc}Day& \text{Mon}& \text{Tue}& \text{Wed}& \text{Thurs}& \text{Fri}& \text{Sat}& \text{Sun}\\ \text{Rainfall}& 0.0& 12.2& 2.1& 0.0& 20.5& 5.5& 1.0\\ \left(\text{in mm}\right)& & & & & & & \end{array}$

(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? [4 MARKS]

Answer 1

Range: 1 Mark
Mean: 2 Marks
Answer: 1 Mark

(i) Range = Highest observation - Lowest observation

Range = 20.5 - 0.0 = 20.5

(ii) $\text{Mean}=\frac{\text{Sum of all observation}}{\text{Total number of observation}}$

$\text{Mean}=\frac{0.0+12.2+2.1+0.0+20.5+5.5+1.0}{7}$

$\text{Mean}=\frac{41.3}{7}=5.9$

(iii) On Mon, Wed, Thurs, Sat, and Sun the rainfall was less than 5.9 mm.

$\Rightarrow$ On 5 days the rainfall was less than the mean rainfall.