City X and City Y is 330 km apart. Carl left City X for City Y at 8.00 a.m. travelling at an average speed of 66 km/h. Oliver left City X later than Carl and caught up with him at 10.00 a.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 Carl arrive in City Y than Oliver? Express your answer in h as a fraction or mixed number.

(a)
From 8.00 a.m. to 10.00 a.m. = 2 h

Distance that Carl covered when Oliver caught up with Carl
= 2 x 66
= 132 km

Time that Oliver took to travel 132 km
= 132 ÷ 72
= 1⁵₆ h

1 h = 60 min
⁵₆ h = ⁵₆ x 60 = 50 min
1⁵₆ h = 1 h 50 min

Time that Oliver left City X:
1 h 50 min before 10.00 a.m. = 8.10 a.m.

(b)
Remaining distance that they had to cover to reach City Y
= 330 - 132
= 198 km

Duration that Oliver had to travel before reaching City Y
= 198 ÷ 72
= 2³₄ h

Duration that Carl had to travel before reaching City Y
= 198 ÷ 66
= 3 h

Duration that Carl took to arrive later than Oliver in City Y
= 3 - 2³₄
= ¹₄ h

Answer(s): (a) 8.10 a.m.; (b) ¹₄ h