Let costC=av+vb According to given question, 30a+30b=7540a+40b=65 On solving (i) and (ii), we get a=21 and b=1800 Now, C=av+vb ⇒dvdC=a−v2bdvdC=0⇒a−v2b=0⇒v=ab=3600⇒v=60kmph
JEE Main 2013 — Mathematics Calculus
The cost of running a bus from A to B, is ₹(av+vb), where v km/h is the average speed of the bus. When the bus travels at 30 km/h, the cost comes out to be ₹75 while at 40 km/h, it is ₹65. Then the most economical speed (in km/h ) of the bus is :
Held on 23 Apr 2013 · Verified 6 Jul 2026.
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