City A and City B are 600 km apart. At 6.37 p.m., Billy is travelling at a uniform speed left City A for City B while Jenson set off from City B to City A along the same road at a uniform speed, which was 10 km/h slower than that of Billy. The two met at 10.37 p.m.
- Find the speed of Billy.
- If Jenson 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 Billy and Jenson to travel from 6.37 p.m. to 10.37 p.m. = 4 h
Average speed of Billy and Jenson
= 600 ÷ 4
= 150 km/h
Billy's speed
= (150 + 10) ÷ 2
= 160 ÷ 2
= 80 km/h
(b)
Jenson's speed
= 80 - 10
= 70 km/h
Distance that Jenson travelled in 4 h
= 4 x 70
= 280 km
Remaining distance that Jenson needed to travel
= 600 - 280
= 320 km
Time that Jenson needed to reach his destination after the two met
= 320 ÷ 70
= 4
4070 = 4
47 h
Answer(s): (a) 80 km/h; (b) 4
47 h