City H and City J are 600 km apart. At 2.35 p.m., Sean is travelling at a uniform speed left City H for City J while Riordan set off from City J to City H along the same road at a uniform speed, which was 6 km/h slower than that of Sean. The two met at 7.35 p.m.
- Find the speed of Sean.
- If Riordan continued to travel at the same speed, how long would it take for him to reach his destination after the two met? Express your answer in mixed number.
(a)
Time taken for Sean and Riordan to travel from 2.35 p.m. to 7.35 p.m. = 5 h
Average speed of Sean and Riordan
= 600 ÷ 5
= 120 km/h
Sean's speed
= (120 + 6) ÷ 2
= 126 ÷ 2
= 63 km/h
(b)
Riordan's speed
= 63 - 6
= 57 km/h
Distance that Riordan travelled in 5 h
= 5 x 57
= 285 km
Remaining distance that Riordan needed to travel
= 600 - 285
= 315 km
Time that Riordan needed to reach his destination after the two met
= 315 ÷ 57
= 5
3057 = 5
1019 h
Answer(s): (a) 63 km/h; (b) 5
1019 h