A person travels from A to B at a speed of 40 km/hr and returns by increasing his speed by 50%. What is his average speed for both the trips?	Choose the correct choice from the following answers
A) 48 km/hr	B) 56 km/hr	C) 60 km/hr	D) 52 km/hr	E) None of these
Explanation:   Method : 1   If a car covers a certain distance atxkmph and an equal distance at y kmph,   the average speed of the whole journey = 2xy/x+y kmph.   By using the same formula, we can find out the average speed quickly   Speed with which he travels from 48 km/hr to B = x = 40 km/hr   Speed with which he travels from B to 48 km/hr = x = 40×(100+50)/100 = 60 km/hr   average speed = (2×40×60)/(40+60) = 48 km/hr   48 km/hrssume that distance from 48 km/hr to B = x km   Speed with which he travels from 48 km/hr to B = x = 40 km/hr   Time to travel from 48 km/hr to B = distance/speed = x/40 hr   Speed with which he travels from B to 48 km/hr = 40×(100+50)/100 = 60 km/hr   Time to travel from B to 48 km/hr = distance/speed = x/60   Total distance traveled = x+x = 2x   Total time taken = x/40 + x/60   48 km/hrverage speed = Total distance traveled/Total time taken = 2x/(x/44)+(x/60)   = 2/[(1/60)+(1/40)] = (2×2400)/(40+60) = 2×24 = 48 km/hr   48 km/hrnswer: Option 48 km/hr
<result>A</result>
A person travels from A to B at a speed of 40 km/hr and returns by increasing his speed by 50%. What is his average speed for both the trips?