Ryan and Seth took part in a 24 km marathon. Ryan 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. Seth ran half his total time at 12 km/h and ran slower for the rest of the time at 9 km/h. If they started the marathon at 7.30 a.m., at what time would each of them finish?
- Ryan
- Seth
(a)
Half of the 24 km marathon = 24 ÷ 2 = 12 km
Time taken by Ryan for the first half of the marathon
= 12 ÷ 8
= 1
12 h
Time taken by Ryan for the last half of the marathon
= 12 ÷ 9
= 1
13 h
Total time taken by Ryan
= 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 7.30 a.m. = 10.20 a.m.
Time that Ryan would finish the marathon = 10.20 a.m.
(b)
Time taken by Seth for the first half of the marathon
= 12 ÷ 12
= 1 h
Time taken by Seth for the last half of the marathon
= 12 ÷ 9
= 1
13 h
Total time taken by Seth
= 1 + 1
13 = 2
13 h
1 h = 60 min
13 h =
13 x 60 = 20 min
2
13 h = 2 h 20 min
2 h 20 min after 7.30 a.m. = 9.50 a.m.
Time that Seth would finish the marathon = 9.50 a.m.
Answer(s): (a) 10.20 a.m.; (b) 9.50 a.m.