A salesman travels a distance of 45 km in 2 hours and 30 minutes. How much faster, in kilometers per hour, on an average, must he travel to make such a trip in 5/6 hour less time?

Question: A salesman travels a distance of 45 km in 2 hours and 30 minutes. How much faster, in kilometers per hour, on an average, must he travel to make such a trip in 5/6 hour less time?

Solution:
Given,
Time = 2 hours and 30 minutes
= (2 + 30/60) hours
= (2 + 1/2) hours
= 5/2 hours

∴ Initial speed = (45 ÷ 5/2) km/h
= (45 × 2/5) km/h
= 18 km/h

New time to travel 45 km = (5/2 - 5/6) = 10/6 = 5/3 hours

∴ New speed = (45 ÷ 5/3) km/h
= (45 × 3/5) km/h
= 27 km/h

∴ Speed should increased = (27 - 18) = 9 km/h