City L and City M are 480 km apart. At 1.52 p.m., Riordan is travelling at a uniform speed left City L for City M while Cody set off from City M to City L along the same road at a uniform speed, which was 10 km/h slower than that of Riordan. The two met at 4.52 p.m.
- Find the speed of Riordan.
- If Cody 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 Cody to travel from 1.52 p.m. to 4.52 p.m. = 3 h
Average speed of Riordan and Cody
= 480 ÷ 3
= 160 km/h
Riordan's speed
= (160 + 10) ÷ 2
= 170 ÷ 2
= 85 km/h
(b)
Cody's speed
= 85 - 10
= 75 km/h
Distance that Cody travelled in 3 h
= 3 x 75
= 225 km
Remaining distance that Cody needed to travel
= 480 - 225
= 255 km
Time that Cody needed to reach his destination after the two met
= 255 ÷ 75
= 3
3075 = 3
25 h
Answer(s): (a) 85 km/h; (b) 3
25 h