City M and City N is 408 km apart. Jenson left City M for City N at 8.00 a.m. travelling at an average speed of 68 km/h. Warren left City M later than Jenson and caught up with him at 12.00 p.m. Warren was travelling at a speed of 102 km/h.

1. At what time did Warren leave City M?
2. How much later did Jenson arrive in City N than Warren? Express your answer in h as a fraction or mixed number.

(a)
From 8.00 a.m. to 12.00 p.m. = 4 h

Distance that Jenson covered when Warren caught up with Jenson
= 4 x 68
= 272 km

Time that Warren took to travel 272 km
= 272 ÷ 102
= 2²₃ h

1 h = 60 min
²₃ h = ²₃ x 60 = 40 min
2²₃ h = 2 h 40 min

Time that Warren left City M:
2 h 40 min before 12.00 p.m. = 9.20 a.m.

(b)
Remaining distance that they had to cover to reach City N
= 408 - 272
= 136 km

Duration that Warren had to travel before reaching City N
= 136 ÷ 102
= 1¹₃ h

Duration that Jenson had to travel before reaching City N
= 136 ÷ 68
= 2 h

Duration that Jenson took to arrive later than Warren in City N
= 2 - 1¹₃
= ²₃ h

Answer(s): (a) 9.20 a.m.; (b) ²₃ h