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A petrol tank is in the form of a frustum of a cone of height 20 m with diameters of its lower and upper ends as 20 m and 50 m respectively. Find the cost of petrol which can fill the tank completely at the rate of Rs. 70 per litre. Also find the surface area of the tank |
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Answer» Capacity of tank `= (1)/(3)pi xx 20 xx (10^(2) + 25^(2) + 10 xx 25)m^(3)` `= pi xx 20xx 325m^(3) = pi xx 20 xx 325l` Cost of petrol `= pi xx 20 xx 325 xx 70 =₹1430000` Slant height `= sqrt(20^(2)+ (25 - 10)^(2))= 25m` Surface area of tank `= pi xx 25(10+25)m^(2) = 2750m^(2)` |
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