(B) Given: Inner radius $(r)$ = $4 \, cm$,Thickness $(t)$ = $0.2 \, cm$. The outer radius $(R)$ = $r + t = 4 + 0.2 = 4.2 \, cm$. The formula for the c

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(B) Given: Inner radius $(r)$ = $4 \, cm$,Thickness $(t)$ = $0.2 \, cm$. The outer radius $(R)$ = $r + t = 4 + 0.2 = 4.2 \, cm$. The formula for the curved surface area of a hemisphere is $2 \pi R^2$. Outer curved surface area = $2 \times \frac{22}{7} \times (4.2)^2$. $= 2 \times \frac{22}{7} \times 4.2 \times 4.2$. $= 2 \times 22 \times 0.6 \times 4.2$. $= 44 \times 2.52 = 110.88 \, cm^2$.

Class 9 Mathematics Surface Areas and Volumes Mix Examples - Surface Areas and Volumes

Medium

$A$ hemispherical metallic bowl is made of steel,$0.2 \, cm$ thick. The inner radius of the bowl is $4 \, cm$. Find the outer curved surface area of the bowl (in $cm^2$).

A
$220$
B
$110.88$
C
$320.44$
D
$156.78$

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Surface Areas and Volumes

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Mix Examples - Surface Areas and Volumes

$A$ sphere and a cylinder of the same radius have equal volumes. By what percentage does the diameter of the cylinder exceed its height?

Medium

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The diameters of two spheres are in the ratio $3: 5$. What is the ratio of their volumes?

Easy

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The total surface area of a closed cylinder is $748\, cm^2$. If its radius is $7\, cm$,find its height (in $cm$).

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The length,breadth,and height of a cuboid are $20\, cm$,$15\, cm$,and $12\, cm$ respectively. Find its total surface area (in $cm^2$).

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State whether the following statement is true or false:
The area of the base of a cylinder is $154 \, cm^{2}$ and its height is $20 \, cm$, then its volume is $3080 \, cm^{3}$.

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$A$ hemispherical metallic bowl is made of steel,$0.2 \, cm$ thick. The inner radius of the bowl is $4 \, cm$. Find the outer curved surface area of the bowl (in $cm^2$).

Similar Questions

$A$ sphere and a cylinder of the same radius have equal volumes. By what percentage does the diameter of the cylinder exceed its height?

The diameters of two spheres are in the ratio $3: 5$. What is the ratio of their volumes?

The total surface area of a closed cylinder is $748\, cm^2$. If its radius is $7\, cm$,find its height (in $cm$).

The length,breadth,and height of a cuboid are $20\, cm$,$15\, cm$,and $12\, cm$ respectively. Find its total surface area (in $cm^2$).

State whether the following statement is true or false:The area of the base of a cylinder is $154 \, cm^{2}$ and its height is $20 \, cm$, then its volume is $3080 \, cm^{3}$.

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State whether the following statement is true or false:
The area of the base of a cylinder is $154 \, cm^{2}$ and its height is $20 \, cm$, then its volume is $3080 \, cm^{3}$.