City Z and City A is 546 km apart. Ben left City Z for City A at 7.00 a.m. travelling at an average speed of 78 km/h. Eric left City Z later than Ben and caught up with him at 11.00 a.m. Eric was travelling at a speed of 117 km/h.

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

(a)
From 7.00 a.m. to 11.00 a.m. = 4 h

Distance that Ben covered when Eric caught up with Ben
= 4 x 78
= 312 km

Time that Eric took to travel 312 km
= 312 ÷ 117
= 2²₃ h

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

Time that Eric left City Z:
2 h 40 min before 11.00 a.m. = 8.20 a.m.

(b)
Remaining distance that they had to cover to reach City A
= 546 - 312
= 234 km

Duration that Eric had to travel before reaching City A
= 234 ÷ 117
= 2 h

Duration that Ben had to travel before reaching City A
= 234 ÷ 78
= 3 h

Duration that Ben took to arrive later than Eric in City A
= 3 - 2
= 1 h

Answer(s): (a) 8.20 a.m.; (b) 1 h