Zane and Dylan took part in a 24 km marathon. Zane ran half the distance at a speed of 8 km/h and ran slower for the rest of the way at a speed of 9 km/h. Dylan ran half his total time at 12 km/h and ran slower for the rest of the time at 10 km/h. If they started the marathon at 6.30 a.m., at what time would each of them finish?
- Zane
- Dylan
(a)
Half of the 24 km marathon = 24 ÷ 2 = 12 km
Time taken by Zane for the first half of the marathon
= 12 ÷ 8
= 1
12 h
Time taken by Zane for the last half of the marathon
= 12 ÷ 9
= 1
13 h
Total time taken by Zane
= 1
12 + 1
13= 2
56 h
1 h = 60 min
56 h =
56 x 60 = 50 min
2
56 h = 2 h 50 min
2 h 50 min after 6.30 a.m. = 9.20 a.m.
Time that Zane would finish the marathon = 9.20 a.m.
(b)
Time taken by Dylan for the first half of the marathon
= 12 ÷ 12
= 1 h
Time taken by Dylan for the last half of the marathon
= 12 ÷ 10
= 1
15 h
Total time taken by Dylan
= 1 + 1
15 = 2
15 h
1 h = 60 min
15 h =
15 x 60 = 12 min
2
15 h = 2 h 12 min
2 h 12 min after 6.30 a.m. = 8.42 a.m.
Time that Dylan would finish the marathon = 8.42 a.m.
Answer(s): (a) 9.20 a.m.; (b) 8.42 a.m.