"Question 1 A wooden bookshelf has external dimensions as follows: Height = 110 cm, Depth = 25 cm, Breadth = 85 cm (see the given 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 cm^2 and the rate of painting is 10 paise per cm^2 , find the total expenses required for polishing and painting the surface of the bookshelf.
Class 9 - Math - Surface Areas and Volumes Page 236"
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Solution-Area to be polished
=(110×85+2×85×25+2×25×110+75×5+2×110×5)
cm square.
=(9350+4250+5500+1500+1100)cm square
=21700cm square
Cost of polishing 20 paise per cm square
=(21700×20/100)
=Rs 4340
Area to be painted
=(9000+3600+6750)cm square
=19350cm square
Cost of painting 10 paise per cm square
Rs(19350×10/100)
=₹1935
Total expense =₹ (4340+1935)
=₹ 6275.
Hope it help⛎⛎⛎
Solution-Area to be polished
=(110×85+2×85×25+2×25×110+75×5+2×110×5)
cm square.
=(9350+4250+5500+1500+1100)cm square
=21700cm square
Cost of polishing 20 paise per cm square
=(21700×20/100)
=Rs 4340
Area to be painted
=(9000+3600+6750)cm square
=19350cm square
Cost of painting 10 paise per cm square
Rs(19350×10/100)
=₹1935
Total expense =₹ (4340+1935)
=₹ 6275.
Hope it help⛎⛎⛎
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