Vaidev and Simon took part in a 24 km marathon. Vaidev ran half the distance at a speed of 9 km/h and ran slower for the rest of the way at a speed of 9 km/h. Simon ran half his total time at 12 km/h and ran slower for the rest of the time at 5 km/h. If they started the marathon at 3.30 a.m., at what time would each of them finish?
- Vaidev
- Simon
(a)
Half of the 24 km marathon = 24 ÷ 2 = 12 km
Time taken by Vaidev for the first half of the marathon
= 12 ÷ 9
= 1
13 h
Time taken by Vaidev for the last half of the marathon
= 12 ÷ 9
= 1
13 h
Total time taken by Vaidev
= 1
13 + 1
13= 2
23 h
1 h = 60 min
23 h =
23 x 60 = 40 min
2
23 h = 2 h 40 min
2 h 40 min after 3.30 a.m. = 6.10 a.m.
Time that Vaidev would finish the marathon = 6.10 a.m.
(b)
Time taken by Simon for the first half of the marathon
= 12 ÷ 12
= 1 h
Time taken by Simon for the last half of the marathon
= 12 ÷ 5
= 2
25 h
Total time taken by Simon
= 1 + 2
25 = 3
25 h
1 h = 60 min
25 h =
25 x 60 = 24 min
3
25 h = 3 h 24 min
3 h 24 min after 3.30 a.m. = 6.54 a.m.
Time that Simon would finish the marathon = 6.54 a.m.
Answer(s): (a) 6.10 a.m.; (b) 6.54 a.m.