City G and City H is 640 km apart. Japheth left City G for City H at 7.00 a.m. travelling at an average speed of 80 km/h. Tommy left City G later than Japheth and caught up with him at 10.00 a.m. Tommy was travelling at a speed of 90 km/h.
- At what time did Tommy leave City G?
- How much later did Japheth arrive in City H than Tommy? 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 Japheth covered when Tommy caught up with Japheth
= 3 x 80
= 240 km
Time that Tommy took to travel 240 km
= 240 ÷ 90
= 2
23 h
1 h = 60 min
23 h =
23 x 60 = 40 min
2
23 h = 2 h 40 min
Time that Tommy left City G:
2 h 40 min before 10.00 a.m. = 7.20 a.m.
(b)
Remaining distance that they had to cover to reach City H
= 640 - 240
= 400 km
Duration that Tommy had to travel before reaching City H
= 400 ÷ 90
= 4
49 h
Duration that Japheth had to travel before reaching City H
= 400 ÷ 80
= 5 h
Duration that Japheth took to arrive later than Tommy in City H
= 5 - 4
49=
59 h
Answer(s): (a) 7.20 a.m.; (b)
59 h
