City N and City P are 576 km apart. At 2.37 p.m., Riordan is travelling at a uniform speed left City N for City P while Simon set off from City P to City N along the same road at a uniform speed, which was 12 km/h slower than that of Riordan. The two met at 6.37 p.m.
- Find the speed of Riordan.
- If Simon 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 Simon to travel from 2.37 p.m. to 6.37 p.m. = 4 h
Average speed of Riordan and Simon
= 576 ÷ 4
= 144 km/h
Riordan's speed
= (144 + 12) ÷ 2
= 156 ÷ 2
= 78 km/h
(b)
Simon's speed
= 78 - 12
= 66 km/h
Distance that Simon travelled in 4 h
= 4 x 66
= 264 km
Remaining distance that Simon needed to travel
= 576 - 264
= 312 km
Time that Simon needed to reach his destination after the two met
= 312 ÷ 66
= 4
4866 = 4
811 h
Answer(s): (a) 78 km/h; (b) 4
811 h