City Z and City A is 408 km apart. Rael left City Z for City A at 7.00 a.m. travelling at an average speed of 68 km/h. Ivan left City Z later than Rael and caught up with him at 10.00 a.m. Ivan was travelling at a speed of 72 km/h.

1. At what time did Ivan leave City Z?
2. How much later did Rael arrive in City A than Ivan? Express your answer in h as a fraction or mixed number.

(a)
From 7.00 a.m. to 10.00 a.m. = 3 h

Distance that Rael covered when Ivan caught up with Rael
= 3 x 68
= 204 km

Time that Ivan took to travel 204 km
= 204 ÷ 72
= 2⁵₆ h

1 h = 60 min
⁵₆ h = ⁵₆ x 60 = 50 min
2⁵₆ h = 2 h 50 min

Time that Ivan left City Z:
2 h 50 min before 10.00 a.m. = 7.10 a.m.

(b)
Remaining distance that they had to cover to reach City A
= 408 - 204
= 204 km

Duration that Ivan had to travel before reaching City A
= 204 ÷ 72
= 2⁵₆ h

Duration that Rael had to travel before reaching City A
= 204 ÷ 68
= 3 h

Duration that Rael took to arrive later than Ivan in City A
= 3 - 2⁵₆
= ¹₆ h

Answer(s): (a) 7.10 a.m.; (b) ¹₆ h