City T and City U are 576 km apart. At 3.24 p.m., Riordan is travelling at a uniform speed left City T for City U while Ben set off from City U to City T along the same road at a uniform speed, which was 8 km/h slower than that of Riordan. The two met at 7.24 p.m.
- Find the speed of Riordan.
- If Ben 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 Riordan and Ben to travel from 3.24 p.m. to 7.24 p.m. = 4 h
Average speed of Riordan and Ben
= 576 ÷ 4
= 144 km/h
Riordan's speed
= (144 + 8) ÷ 2
= 152 ÷ 2
= 76 km/h
(b)
Ben's speed
= 76 - 8
= 68 km/h
Distance that Ben travelled in 4 h
= 4 x 68
= 272 km
Remaining distance that Ben needed to travel
= 576 - 272
= 304 km
Time that Ben needed to reach his destination after the two met
= 304 ÷ 68
= 4
3268 = 4
817 h
Answer(s): (a) 76 km/h; (b) 4
817 h