City U and City V is 360 km apart. Vaidev left City U for City V at 9.00 a.m. travelling at an average speed of 60 km/h. Archie left City U later than Vaidev and caught up with him at 11.00 a.m. Archie was travelling at a speed of 80 km/h.

1. At what time did Archie leave City U?
2. How much later did Vaidev arrive in City V than Archie? Express your answer in h as a fraction or mixed number.

(a)
From 9.00 a.m. to 11.00 a.m. = 2 h

Distance that Vaidev covered when Archie caught up with Vaidev
= 2 x 60
= 120 km

Time that Archie took to travel 120 km
= 120 ÷ 80
= 1¹₂ h

1 h = 60 min
¹₂ h = ¹₂ x 60 = 30 min
1¹₂ h = 1 h 30 min

Time that Archie left City U:
1 h 30 min before 11.00 a.m. = 9.30 a.m.

(b)
Remaining distance that they had to cover to reach City V
= 360 - 120
= 240 km

Duration that Archie had to travel before reaching City V
= 240 ÷ 80
= 3 h

Duration that Vaidev had to travel before reaching City V
= 240 ÷ 60
= 4 h

Duration that Vaidev took to arrive later than Archie in City V
= 4 - 3
= 1 h

Answer(s): (a) 9.30 a.m.; (b) 1 h