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 cm³ ?
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Verified answer
Answer:
Surface area of 8 spheres = 8×4×722×(221)2cm2=11088cm2
Surface area of 8 cylinders = 8×2×22/7×1.5×7cm2= 528cm2
Curved surf ace area of the top of 8 cylinder = 8×22/7 ×(1.5)2cm2=56.57cm2
∴ Cost of painting = Rs. {(11088−56.57)×25/100+528×5/100}= Rs.2784.26
Step-by-step explanation:
Cost of painting= Rs. 2784.26