It is required to make a closed cylindrical tank of height $ 1 \mathrm{~m} $ and base diameter $ 140 \mathrm{~cm} $ from a metal sheet. How many square metres of the sheet are required for the same?

AcademicMathematicsNCERTClass 9

Given:

It is required to make a closed cylindrical tank of height $1\ m$ and base diameter $140\ cm$ from a metal sheet.

To do:

We have to find the area of the sheet required. 

Solution:

Height of the cylinder $(h) = 1\ m$

$= 100\ cm$

Diameter of the cylinder $= 140\ cm$
This implies,

Radius $(r)=\frac{140}{2}$

$=70 \mathrm{~cm}$

Therefore,

Total surface area $=2 \pi r(h+r)$

$=2 \times \frac{22}{7} \times 70(100+70)$

$=440 \times 170$

$=74800 \mathrm{~cm}^{2}$

$=\frac{74800}{100 \times 100} \mathrm{~m}^{2}$

$=7.48 \mathrm{~m}^{2}$

Hence, the total surface area $7.48 \mathrm{~m}^{2}$.

raja
Updated on 10-Oct-2022 13:46:29

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