City K and City L are 580 km apart. At 3.36 p.m., Sean is travelling at a uniform speed left City K for City L while Japheth set off from City L to City K along the same road at a uniform speed, which was 12 km/h slower than that of Sean. The two met at 8.36 p.m.
- Find the speed of Sean.
- If Japheth 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 Sean and Japheth to travel from 3.36 p.m. to 8.36 p.m. = 5 h
Average speed of Sean and Japheth
= 580 ÷ 5
= 116 km/h
Sean's speed
= (116 + 12) ÷ 2
= 128 ÷ 2
= 64 km/h
(b)
Japheth's speed
= 64 - 12
= 52 km/h
Distance that Japheth travelled in 5 h
= 5 x 52
= 260 km
Remaining distance that Japheth needed to travel
= 580 - 260
= 320 km
Time that Japheth needed to reach his destination after the two met
= 320 ÷ 52
= 6
852 = 6
213 h
Answer(s): (a) 64 km/h; (b) 6
213 h