Question

The fuel cost per hour for running a train is proportional to the square of the speed it generates in km per hour. If the fuel costs ₹ 48 per hour at a speed of 16 km per hour and the fixed charges to run the train amount to ₹ 1200 per hour. Assume the speed of the train as v km/h.

The most economical speed to run the train is:

Options

• 18 km/h

• 5 km/h

• 80 km/h

• 40 km/h

Answer 1

80 km/h

Explanation:

`"dC"/"dv" = 375/4 - 600000/"v"^2`

Let `"dC"/"dv"` = 0

v = 80 km/h