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Probability
Question
A wooden bookshelf has external dimensions as follows: Height = 110 cm, Depth = 25 cm, Breadth = 85 cm (see figure). The thickness of the plank is 5 cm everywhere. The external faces are to be polished and the inner faces are to be painted. If the rate of polishing is 20 paise per cm2 and the rate of painting is 10 paise per cm2, find the total expenses required for polishing and painting the surface of the bookshelf.
Solution
Surface area to be polished = [(110 x 85) + 2(110 x 25) + 2(85 x 25) + 2(110 x 5) + 4(75 x 5)]
= (9350 + 5500 + 4250 + 1100 + 1500) cm2 = 21700 cm2
∴ Expenses required for polishing @ 20 paise per cm2
= 21700 x 20 paise
Surface area to be painted
= [2(20 x 90) + 6(75 x 20) + (75 x 90)]
= (3600 + 9000 + 6750) cm2 = 19350 cm2
∴ Expenses required for painting @ 10 paise per cm2
= 19350 x 10 paise
∴ Total expenses required for polishing and painting the surface of the bookshelf
= र 4340 + र 1935 = र 6275.
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Some More Questions From Probability Chapter
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Mock Test Series
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