City S and City T are 387 km apart. At 5.24 p.m., Seth is travelling at a uniform speed left City S for City T while Tommy set off from City T to City S along the same road at a uniform speed, which was 9 km/h slower than that of Seth. The two met at 8.24 p.m.
- Find the speed of Seth.
- If Tommy 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 Seth and Tommy to travel from 5.24 p.m. to 8.24 p.m. = 3 h
Average speed of Seth and Tommy
= 387 ÷ 3
= 129 km/h
Seth's speed
= (129 + 9) ÷ 2
= 138 ÷ 2
= 69 km/h
(b)
Tommy's speed
= 69 - 9
= 60 km/h
Distance that Tommy travelled in 3 h
= 3 x 60
= 180 km
Remaining distance that Tommy needed to travel
= 387 - 180
= 207 km
Time that Tommy needed to reach his destination after the two met
= 207 ÷ 60
= 3
2760 = 3
920 h
Answer(s): (a) 69 km/h; (b) 3
920 h