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The cost of running a bus from A to B, is ₹ (a v+ b v ), where v ~km / h is the average speed of the bus. When the bus travels at 30 ~km / h, the…

JEE Main 2013 — Mathematics Calculus

2013mcqmedium

The cost of running a bus from AAA to BBB, is ₹(av+bv)₹\left(a v+\frac{b}{v}\right)₹(av+vb​), where v km/hv \mathrm{~km} / \mathrm{h}v km/h is the average speed of the bus. When the bus travels at 30 km/h30 \mathrm{~km} / \mathrm{h}30 km/h, the cost comes out to be ₹75₹ 75₹75 while at 40 km/h40 \mathrm{~km} / \mathrm{h}40 km/h, it is ₹65₹ 65₹65. Then the most economical speed (in km/h\mathrm{km} / \mathrm{h}km/h ) of the bus is :

Official previous-year question

Held on 23 Apr 2013 · Verified 6 Jul 2026.

Options

  1. A

    45

  2. B

    50

  3. C

    60

  4. D

    40

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