Justin started driving from Town S towards Town T at 15 40 at an average speed of 60 km/h. Pierre began driving from Town S towards Town T at 17 20 at an average speed of 100 km/h.
- At what time did Pierre pass Justin on the road?
- 114 hours after passing Justin, Pierre reached Town T. At what time did Justin reach Town T?
(a)
From 15 40 to 17 20 = 1 h 40 min
Time that Justin travelled before Pierre started driving = 1 h 40 min
1 h = 60 min
1 h 40 min = 1
4060 h = 1
23 h
Distance that Justin travelled before Pierre started driving
= 1
23 x 60
=
53 x 60
= 100 km
Difference between Pierre's and Justin's speed
= 100 - 60
= 40 km/h
Time that Pierre took to catch up with Justin
= 100 ÷ 40
= 2.5 h
= 2 h 30 min
2 h 30 min after 17 20 = 19 50
Time that Pierre passed Justin on the road = 19 50
(b)
1
14 h = 1 h 15 min
Total time that Pierre travelled
= 1 h 15 min + 2 h 30 min
= 3 h 45 min
3 h 45 min = 3
4560h = 3
34h
Distance between Town S and Town T
= 3
34 x 100
= 375 km
Time that Justin travelled from Town S to Town T
= 375 ÷ 60
= 6.25 h
= 6 h 15 min
6 h 15 min after 15 40 = 21 55
Time that Justin reached Town T = 21 55
Answer: (a) 19 50; (b) 21 55