City P and City Q are 480 km apart. At 4.12 p.m., Lee is travelling at a uniform speed left City P for City Q while Vincent set off from City Q to City P along the same road at a uniform speed, which was 8 km/h slower than that of Lee. The two met at 8.12 p.m.
- Find the speed of Lee.
- If Vincent 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 Lee and Vincent to travel from 4.12 p.m. to 8.12 p.m. = 4 h
Average speed of Lee and Vincent
= 480 ÷ 4
= 120 km/h
Lee's speed
= (120 + 8) ÷ 2
= 128 ÷ 2
= 64 km/h
(b)
Vincent's speed
= 64 - 8
= 56 km/h
Distance that Vincent travelled in 4 h
= 4 x 56
= 224 km
Remaining distance that Vincent needed to travel
= 480 - 224
= 256 km
Time that Vincent needed to reach his destination after the two met
= 256 ÷ 56
= 4
3256 = 4
47 h
Answer(s): (a) 64 km/h; (b) 4
47 h