-er the following questions.
04 X 04 = 16
A cone and a hemisphere are joined on either sides of a cylinder. These
solids 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 Rs.10
per 100cm2
Answers
Answer:
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}
r
+
h
2
l = \sqrt{7^2 + 24^2}
7
2
+24
2
l = \sqrt{625}
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 r2πrh+πrl+2πr
= 2\times \frac{22}{7 }\times 30 + \frac{22}{7 }\times 7 \times 25 + 2\times \frac{22}{7 }\times 72×
7
22
×30+
7
22
×7×25+2×
7
22
×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