At 13 20, Henry left Town K for Town L, driving at a speed of 90 km/h. At 15 20, Vaidev also left Town K for Town L driving at a certain speed. Both of them did not change their speed throughout the journey. At 18 20, both of them passed a market that was 270 km away from Town L. How many minutes earlier did Vaidev reach Town L than Henry?
Duration that Henry travelled from 13 20 to 18 20 = 5 h
Distance that Henry travelled
= 5 x 90
= 450 km
Distance between Town K and Town L
= 450 + 270
= 720 km
Since Vaidev passed the market at the same time as Henry, it means that Vaidev travelled 450 km in 3 hours.
Vaidev's speed during the journey
= 450 ÷ 3
= 150 km/h
Duration that Vaidev took to reach Town L after passing the market
= 270 ÷ 150
= 1.8 h
Duration that Henry took to reach Town L after passing the market
= 270 ÷ 90
= 3 h
Difference between the time they took to reach Town L
= 3 - 1.8
= 1.2 h
1 h = 60 min
1.2 h = 1.2 x 60 = 72 min
Vaidev reached Town L 72 minutes earlier than Henry.
Answer(s): 72 min