City D and City E are 592 km apart. At 6.47 p.m., Tom is travelling at a uniform speed left City D for City E while Sean set off from City E to City D along the same road at a uniform speed, which was 12 km/h slower than that of Tom. The two met at 10.47 p.m.
- Find the speed of Tom.
- If Sean 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 Tom and Sean to travel from 6.47 p.m. to 10.47 p.m. = 4 h
Average speed of Tom and Sean
= 592 ÷ 4
= 148 km/h
Tom's speed
= (148 + 12) ÷ 2
= 160 ÷ 2
= 80 km/h
(b)
Sean's speed
= 80 - 12
= 68 km/h
Distance that Sean travelled in 4 h
= 4 x 68
= 272 km
Remaining distance that Sean needed to travel
= 592 - 272
= 320 km
Time that Sean needed to reach his destination after the two met
= 320 ÷ 68
= 4
4868 = 4
1217 h
Answer(s): (a) 80 km/h; (b) 4
1217 h