City Y and City Z are 420 km apart. At 4.22 p.m., Seth is travelling at a uniform speed left City Y for City Z while Ian 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 Seth. The two met at 7.22 p.m.
- Find the speed of Seth.
- If Ian 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 Seth and Ian to travel from 4.22 p.m. to 7.22 p.m. = 3 h
Average speed of Seth and Ian
= 420 ÷ 3
= 140 km/h
Seth's speed
= (140 + 8) ÷ 2
= 148 ÷ 2
= 74 km/h
(b)
Ian's speed
= 74 - 8
= 66 km/h
Distance that Ian travelled in 3 h
= 3 x 66
= 198 km
Remaining distance that Ian needed to travel
= 420 - 198
= 222 km
Time that Ian needed to reach his destination after the two met
= 222 ÷ 66
= 3
2466 = 3
411 h
Answer(s): (a) 74 km/h; (b) 3
411 h