A car travels from Mumbai to Pune at a average speed of 50 km/hr and back from
Pune to Mumbai at an average speed of 75 km/hr. If the distance from Mumbai to
Pune is 150 km, what is the average speed for the round trip from Mumbai to
Pune and back?
from Mumbai to Pune:
S = 50km/hr
D = 150km
T = ?
S = D/T
50 = 150/T
T = 150/50 = 3hrs
from Pune to Mumbai:
S = 75km/hr
D = 150km
T = ?
S = D/T
75 = 150/T
T = 150/75 = 2hrs
average speed = total distance/total time
= 150 + 150/ 3 + 2 = 300/5 = 60km/hr
thus, average speed = 60km/hr.
hope this helps!!!!!