ICSE Board Question Based on Mensuration Chapter of M.L Aggarwal for class10

In this question width,diameter and slant height of a conical tent is given.

Also find the cost of the canvas at the rate of Rs 80 per metre.

This is the Question Number 14, Exercise 17.2 of M.L Aggarwal.

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# Find what length of canvas 2 m in width is required to make a conical tent 20 m in diameter and 42 m in slant height allowing 10% for folds and the stitching. Also find the cost of the canvas at the rate of Rs 80 per metre.

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This answer was edited.Given diameter of the conical tent, d = 20 mradius, r = d/2 = 20/2 = 10 mSlant height,l= 42 mCurved surface area of the conical tent = πrl= (22/7)×10×42= 22×10×6= 1320 m^{2}So the area of canvas required is 1320 m^{2}.Since 10% of this area is used for folds and stitches, actual cloth needed = 1320+ 10% of 1320= 1320 + (10/100)×1320= 1320+132= 1452 m^{2}Width of the cloth = 2mLength of the cloth = Area/width = 1452/2 = 726 mCost of canvas = Rs.80 per metre.Total cost = 80×726 = Rs. 58080Hence the total cost of the canvas is Rs. 58080.