Question

A bus leaves Los Angeles at 8am moving northeast at 60 mph. Three hours later, a truck leaves the same place traveling 1 2/3 times faster than the bus on the same route. How long will it take for the truck to catch up the bus?

Answer 1

The truck will catch up the bus after 4.5 hours

Explanation:

∵ The speed of the bus is 60 mph

∴ The speed of the truck = 60 ×
`1(2)/(3)`=60 ×
`(5)/(3)`= 100 mph

∵ The bus move befor the truck by 3 hours

∴ The bus move distance = 60 × 3 = 180 miles when the truck starts to move

∴ D truck - D bus = 180

∵ D truck = 100 × t = 100t

∵ D bus = 60 × t = 60t they meet each other at the same time

∴ 100t - 60t = 180

∴ 40t = 180

∴ t = 180/40 = 4.5

∴ They meet each other after 4.5 hours

∴ The truck catch the bus after 4.5 hours from his moving

Note: you can solve it by another way that let the time of the bus is t so the time of the truck will be t - 3 and put D bus = D truck