City H and City J is 240 km apart. Lee left City H for City J at 7.00 a.m. travelling at an average speed of 60 km/h. Riordan left City H later than Lee and caught up with him at 9.00 a.m. Riordan was travelling at a speed of 80 km/h.
- At what time did Riordan leave City H?
- How much later did Lee arrive in City J than Riordan? Express your answer in h as a fraction or mixed number.
(a)
From 7.00 a.m. to 9.00 a.m. = 2 h
Distance that Lee covered when Riordan caught up with Lee
= 2 x 60
= 120 km
Time that Riordan took to travel 120 km
= 120 ÷ 80
= 1
12 h
1 h = 60 min
12 h =
12 x 60 = 30 min
1
12 h = 1 h 30 min
Time that Riordan left City H:
1 h 30 min before 9.00 a.m. = 7.30 a.m.
(b)
Remaining distance that they had to cover to reach City J
= 240 - 120
= 120 km
Duration that Riordan had to travel before reaching City J
= 120 ÷ 80
= 1
12 h
Duration that Lee had to travel before reaching City J
= 120 ÷ 60
= 2 h
Duration that Lee took to arrive later than Riordan in City J
= 2 - 1
12=
12 h
Answer(s): (a) 7.30 a.m.; (b)
12 h
