Question

a cone and a hemisphere are joined on either sides of a cylinder these solides have radius 7cm each if the total height of the solid is 61cm and the height of the cylinder is 30cm find the cost of painting the outer surface of the solid at the rate of 10per 100cm2 ​

Answer 1

Answer:

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Answer 2

The cost of painting is Rs. 191.4

Step-by-step explanation:

total height of the solid = 61 cm

height of the cylinder =  30 cm

radius = 7 cm

height of the hemisphere = 7 cm

then height of the cone =  61- (30+h) = 24 cm

l = $\sqrt{r^+h^2}$

l = $\sqrt{7^2 + 24^2}$

l = $\sqrt{625}$

l = 25 cm

surface area to be paint of solid = CSA of cylinder + CSA of cone + CSA of hemisphere

= $2\pi rh + \pi rl + 2\pi r$

= $2\times \frac{22}{7 }\times 30 + \frac{22}{7 }\times 7 \times 25 + 2\times \frac{22}{7 }\times 7$

on solving we get

= 1320 + 550 + 44

= 1914 cm²

cost of painting is 10 per 100 cm² =  ​

cost of painting 1 cm² = Rs. 0.1

cost of painting 1914 cm²  = 1914 × 0.1 = Rs. 191.4

hence ,

The cost of painting is Rs. 191.4

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