Q.

Draw an isometric sketch for the shape obtained by joining two hemispheres of radius  5cm   and then find the surface area and volume of the shape obtained.


Grade: Grade 10


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a

219.35c m 2 and423.65c m 3  

b

256.36c m 2 and128.45c m 2  

c

314.15c m 2 and450.38c m 3  

d

314.15c m 2 and523.59c m 3   

answer is D.

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Detailed Solution

IMG_256
Radius of given hemisphere =  5cm  
As, sphere is obtained by adjoining two hemispheres. Therefore its radius will also be the same as the radius of the hemisphere.
Radius of sphere =  5cm  
Also, we know that volume of sphere is given as =  4 3 π r 3  
Substituting value of ‘r’ in above volume formula we have
Volume(V)= 4 3 × 22 7 × (5) 3 Volume(V)= 4 3 × 22 7 ×5×5×5 Volume(V)= 4 3 × 22 7 ×125 Volume(V)= 11000 21 Volume(V)=523.59  
Therefore, we see that volume of sphere of radius  5cm   is  523.59c m 3  .
Now, to find the surface area of the sphere. We use a mensuration formula.
Surface Area =  4π r 2  
Substituting value of ‘r’ in above formula we have,
Surfacearea(A)=4× 22 7 × (5) 2 Surfacearea(A)=4× 22 7 ×5×5 Surfacearea(A)= 2200 7 Surfacearea(A)=314.15  
Therefore, from above we see that the surface area of the sphere is  314.15c m 2   .
So, the correct Ans is Option 4.
 
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