Question -
Answer -
Given,
Radius of thehemispherical end (r) = 7 cm
Height of the solid =(h + 2r) = 104 cm
⇒ h + 2r = 104
⇒ h = 104 − (2 × 7)
So, h = 90 cm
We know that,
The curved surfacearea of the cylinder (S1) = 2 πr h
S1= 2π(7)(90)
S1 =3960 cm2
Next,
Curved surface area ofthe two hemisphere (S2) = 2 (2πr2)
S2 = 2x 2π(7)2
S2 =616 cm2
Therefore,
The total curvedsurface area of the solid (S) = Curved surface area of the cylinder + Curvedsurface area of the two hemispheres
S = S1 +S2
S = 3960 + 616
S = 4576 cm2 =45.76 dm2
Given that the cost ofpolishing the 1 dm2 surface of the solid is Rs. 10
So, the cost ofpolishing the 45.76 dm2 surface of the solid = Rs (10 x 45.76)= Rs. 457.6
Therefore,
The cost of polishingthe whole surface of the solid is Rs. 457.60