City M and City N are 310 km apart. At 4.18 p.m., Justin is travelling at a uniform speed left City M for City N while Vaidev set off from City N to City M along the same road at a uniform speed, which was 5 km/h slower than that of Justin. The two met at 6.18 p.m.
- Find the speed of Justin.
- If Vaidev 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 Vaidev to travel from 4.18 p.m. to 6.18 p.m. = 2 h
Average speed of Justin and Vaidev
= 310 ÷ 2
= 155 km/h
Justin's speed
= (155 + 5) ÷ 2
= 160 ÷ 2
= 80 km/h
(b)
Vaidev's speed
= 80 - 5
= 75 km/h
Distance that Vaidev travelled in 2 h
= 2 x 75
= 150 km
Remaining distance that Vaidev needed to travel
= 310 - 150
= 160 km
Time that Vaidev needed to reach his destination after the two met
= 160 ÷ 75
= 2
1075 = 2
215 h
Answer(s): (a) 80 km/h; (b) 2
215 h