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The most economical speed to run the train is:

(a) 18 km/h   (b)5 km/h  (c) 80 km/h        (d) 40 km/h 

 

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Question 48 The most economical speed to run the train is: (a) 18 km/h (b)5 km/h (c) 80 km/h (d) 40 km/h We need to find minimise Cost Now, Cost = C(v) = šŸ‘šŸ•šŸ“/šŸ’ š’— + šŸ”šŸŽšŸŽšŸŽšŸŽšŸŽ/š’— Differentiating w.r.t v Cā€™(v) = šŸ‘šŸ•šŸ“/šŸ’ āˆ’ šŸ”šŸŽšŸŽšŸŽšŸŽšŸŽ/š’—^šŸ Putting Cā€™(v) = 0 0 = 375/4 āˆ’ 600000/š‘£^2 600000/š‘£^2 = 375/4 600000 Ɨ4/375 = š‘£^2 600000 Ɨ4/375 = š‘£^2 1600 Ɨ 4 = š’—^šŸ 40 Ɨ 2 = š’— 80 = š’— š’— = 80 km/hr So, the correct answer is (c)

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Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 13 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.