City P and City Q are 440 km apart. At 3.13 p.m., Justin is travelling at a uniform speed left City P for City Q while Carl set off from City Q to City P along the same road at a uniform speed, which was 10 km/h slower than that of Justin. The two met at 5.13 p.m.
- Find the speed of Justin.
- If Carl 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 Justin and Carl to travel from 3.13 p.m. to 5.13 p.m. = 2 h
Average speed of Justin and Carl
= 440 ÷ 2
= 220 km/h
Justin's speed
= (220 + 10) ÷ 2
= 230 ÷ 2
= 115 km/h
(b)
Carl's speed
= 115 - 10
= 105 km/h
Distance that Carl travelled in 2 h
= 2 x 105
= 210 km
Remaining distance that Carl needed to travel
= 440 - 210
= 230 km
Time that Carl needed to reach his destination after the two met
= 230 ÷ 105
= 2
20105 = 2
421 h
Answer(s): (a) 115 km/h; (b) 2
421 h