City F and City G is 490 km apart. David left City F for City G at 7.00 a.m. travelling at an average speed of 70 km/h. Mark left City F later than David and caught up with him at 10.00 a.m. Mark was travelling at a speed of 72 km/h.
- At what time did Mark leave City F?
- How much later did David arrive in City G than Mark? 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 David covered when Mark caught up with David
= 3 x 70
= 210 km
Time that Mark took to travel 210 km
= 210 ÷ 72
= 2
1112 h
1 h = 60 min
1112 h =
1112 x 60 = 55 min
2
1112 h = 2 h 55 min
Time that Mark left City F:
2 h 55 min before 10.00 a.m. = 7.05 a.m.
(b)
Remaining distance that they had to cover to reach City G
= 490 - 210
= 280 km
Duration that Mark had to travel before reaching City G
= 280 ÷ 72
= 3
89 h
Duration that David had to travel before reaching City G
= 280 ÷ 70
= 4 h
Duration that David took to arrive later than Mark in City G
= 4 - 3
89=
19 h
Answer(s): (a) 7.05 a.m.; (b)
19 h