City W and City X are 450 km apart. At 1.20 p.m., Liam is travelling at a uniform speed left City W for City X while Harry set off from City X to City W along the same road at a uniform speed, which was 6 km/h slower than that of Liam. The two met at 4.20 p.m.
- Find the speed of Liam.
- If Harry 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 Liam and Harry to travel from 1.20 p.m. to 4.20 p.m. = 3 h
Average speed of Liam and Harry
= 450 ÷ 3
= 150 km/h
Liam's speed
= (150 + 6) ÷ 2
= 156 ÷ 2
= 78 km/h
(b)
Harry's speed
= 78 - 6
= 72 km/h
Distance that Harry travelled in 3 h
= 3 x 72
= 216 km
Remaining distance that Harry needed to travel
= 450 - 216
= 234 km
Time that Harry needed to reach his destination after the two met
= 234 ÷ 72
= 3
1872 = 3
14 h
Answer(s): (a) 78 km/h; (b) 3
14 h