City X and City Y is 360 km apart. Owen left City X for City Y at 11.00 a.m. travelling at an average speed of 60 km/h. Oliver left City X later than Owen and caught up with him at 2.00 p.m. Oliver was travelling at a speed of 72 km/h.

1. At what time did Oliver leave City X?
2. How much later did Owen arrive in City Y than Oliver? Express your answer in h as a fraction or mixed number.

(a)
From 11.00 a.m. to 2.00 p.m. = 3 h

Distance that Owen covered when Oliver caught up with Owen
= 3 x 60
= 180 km

Time that Oliver took to travel 180 km
= 180 ÷ 72
= 2¹₂ h

1 h = 60 min
¹₂ h = ¹₂ x 60 = 30 min
2¹₂ h = 2 h 30 min

Time that Oliver left City X:
2 h 30 min before 2.00 p.m. = 11.30 a.m.

(b)
Remaining distance that they had to cover to reach City Y
= 360 - 180
= 180 km

Duration that Oliver had to travel before reaching City Y
= 180 ÷ 72
= 2¹₂ h

Duration that Owen had to travel before reaching City Y
= 180 ÷ 60
= 3 h

Duration that Owen took to arrive later than Oliver in City Y
= 3 - 2¹₂
= ¹₂ h

Answer(s): (a) 11.30 a.m.; (b) ¹₂ h