2. The front compound wall of a house is
decorated by wooden spheres of diameter 21
cm. placed on small supports as shown in Fig
13.32. Eight such spheres are used for this
purpose, and are to be painted silver. Each
support is a cylinder of radius 1.5 cm and height
7 cm and is to be painted black. Find the cost
of paint required if silver paint costs 25 paise
per cm and black paint costs 5 paise per cm?. .
Fig. 13.32
Answers
Answered by
3
Answer:
Surface area of 8 spheres = 8×4×
7
22
×(
2
21
)
2
cm
2
=11088cm
2
Surface area of 8 cylinders = 8×2×
7
22
×1.5×7cm
2
=528cm
2
Curved surface area of the top of 8 cylinder = 8×
7
22
×(1.5)
2
cm
2
=56.57cm
2
∴ Cost of painting = Rs. {(11088−56.57)×
100
25
+528×
100
5
}=Rs.2784.26
Answered by
1
Answer:
7 cm
Step-by-step explanation:
radius of sphere = diameter/2 = 21/2cm
radius of cylinder = 1.5cm
height of cylinder = 7 cm
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