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 

 

Slide127.JPG

Advertisement

Slide128.JPG

Advertisement

  1. Class 12
  2. Solutions of Sample Papers and Past Year Papers - for Class 12 Boards

Transcript

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) = ๐Ÿ‘๐Ÿ•๐Ÿ“/๐Ÿ’ ๐’— + ๐Ÿ”๐ŸŽ๐ŸŽ๐ŸŽ๐ŸŽ๐ŸŽ/๐’— Differentiating w.r.t v Cโ€™(v) = ๐Ÿ‘๐Ÿ•๐Ÿ“/๐Ÿ’ โˆ’ ๐Ÿ”๐ŸŽ๐ŸŽ๐ŸŽ๐ŸŽ๐ŸŽ/๐’—^๐Ÿ Putting Cโ€™(v) = 0 0 = 375/4 โˆ’ 600000/๐‘ฃ^2 600000/๐‘ฃ^2 = 375/4 600000 ร—4/375 = ๐‘ฃ^2 600000 ร—4/375 = ๐‘ฃ^2 1600 ร— 4 = ๐’—^๐Ÿ 40 ร— 2 = ๐’— 80 = ๐’— ๐’— = 80 km/hr So, the correct answer is (c)

About the Author

Davneet Singh's photo - Teacher, Engineer, Marketer
Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 10 years. He provides courses for Maths and Science at Teachoo.