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

DayMonTueWedThursFriSatSun
Rainfall (in mm)0.012.22.10.020.55.51.0

$(i)$. 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."

AcademicMathematicsNCERTClass 7

Given:

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

To do:

We have to 

(i) Find the range of the rainfall in the above data.

(ii) Find the mean rainfall for the week.

(iii) Find on how many days the rainfall was less than the mean rainfall.

Solution:

(i) Highest of the rainfall (in mm) $=20.5$

Lowest of the rainfall (in mm) $=0.0$

Range of the rainfall $=$ Highest rainfall $-$ Lowest rainfall

$=20.5-0.0$

$=20.5\ mm$

(ii) Total number of days$=7$

Record of the rainfall (in mm) $= 0.0, 12.2, 2.1, 0.0, 20.5, 5.5, 1.0$

Mean of the rainfall (in mm) $=\frac{ \text { Sum of rainfalls (in mm) }}{ \text { Number of days }}$

$=\frac{(0.0+12.2+2.1+0.0+20.5+5.5+1.0)}{7}$

$=\frac{41.3}{7}$

$=5.9\ mm$

(iii) On 5 days rainfall was less than the mean rainfall i.e., Monday, Wednesday, Thursday, Saturday, and Sunday.

raja
Updated on 10-Oct-2022 13:33:20

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