City Y and City Z are 600 km apart. At 2.19 p.m., Rael is travelling at a uniform speed left City Y for City Z while Japheth set off from City Z to City Y along the same road at a uniform speed, which was 8 km/h slower than that of Rael. The two met at 7.19 p.m.
- Find the speed of Rael.
- 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 Rael and Japheth to travel from 2.19 p.m. to 7.19 p.m. = 5 h
Average speed of Rael and Japheth
= 600 ÷ 5
= 120 km/h
Rael's speed
= (120 + 8) ÷ 2
= 128 ÷ 2
= 64 km/h
(b)
Japheth's speed
= 64 - 8
= 56 km/h
Distance that Japheth travelled in 5 h
= 5 x 56
= 280 km
Remaining distance that Japheth needed to travel
= 600 - 280
= 320 km
Time that Japheth needed to reach his destination after the two met
= 320 ÷ 56
= 5
4056 = 5
57 h
Answer(s): (a) 64 km/h; (b) 5
57 h