Use Coupon: CART20 and get 20% off on all online Study Material

Total Price: Rs.

There are no items in this cart.
Continue Shopping
Grade: 12
        The cost of fuel for running a bus is proportional to the square of the speed generated in km/ hr . It costs rs.48 per hour when the bus is moving at the speed of 20 km per hour. What is the most economical speed if the fixed charges are rs.108 for an hour,over and above the running charges
2 years ago

Answers : (2)

24731 Points
let F= fuel cost V= speed and K= constant
for the given condition, 48= K x 202
=) K= 3/25

as fixed charge is in Rs/hr, it is proportional to 1/V. (time= distance/velocity)
for minima fuel cost, dF/dV = 0
=) d/dV (KV2 + A/V) A= rs 108/ hr
=) 2KV - A/V2 = 0
=) 2KV = A/V2
=) V3 = A/(2*(3/25)) = 108/(3/25)=900
=) V = 9.65 kmph
2 years ago
Ramesh saini
11 Points
							let speed =v and cost c=kv² ,if cost is 48 then speed is20km/h then 48=k(20)² then k=3/25 now total cost=C=3/25×v² × x/v +108x/v     (let distance be xkm) ,thenC=3vx/25 +108x/v now dC/dv=3x/25-108x/v²     for max or min dC/dX=0 then we have v=30 now if v=30 then d²C/dx² is +ve so cost is minimum when v=30km/h
2 years ago
Think You Can Provide A Better Answer ?
Answer & Earn Cool Goodies

Course Features

  • 731 Video Lectures
  • Revision Notes
  • Previous Year Papers
  • Mind Map
  • Study Planner
  • NCERT Solutions
  • Discussion Forum
  • Test paper with Video Solution

Course Features

  • 51 Video Lectures
  • Revision Notes
  • Test paper with Video Solution
  • Mind Map
  • Study Planner
  • NCERT Solutions
  • Discussion Forum
  • Previous Year Exam Questions

Ask Experts

Have any Question? Ask Experts

Post Question

Answer ‘n’ Earn
Attractive Gift
To Win!!! Click Here for details