Asher and Sam took part in a 42 km marathon. Asher 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. Sam ran half his total time at 10 km/h and ran slower for the rest of the time at 7 km/h. If they started the marathon at 4.30 a.m., at what time would each of them finish?
- Asher
- Sam
(a)
Half of the 42 km marathon = 42 ÷ 2 = 21 km
Time taken by Asher for the first half of the marathon
= 21 ÷ 9
= 2
13 h
Time taken by Asher for the last half of the marathon
= 21 ÷ 9
= 2
13 h
Total time taken by Asher
= 2
13 + 2
13= 4
23 h
1 h = 60 min
23 h =
23 x 60 = 40 min
4
23 h = 4 h 40 min
4 h 40 min after 4.30 a.m. = 9.10 a.m.
Time that Asher would finish the marathon = 9.10 a.m.
(b)
Time taken by Sam for the first half of the marathon
= 21 ÷ 10
= 2
110 h
Time taken by Sam for the last half of the marathon
= 21 ÷ 7
= 3 h
Total time taken by Sam
= 2
110 + 3
= 5
110 h
1 h = 60 min
110 h =
110 x 60 = 6 min
5
110 h = 5 h 6 min
5 h 6 min after 4.30 a.m. = 9.36 a.m.
Time that Sam would finish the marathon = 9.36 a.m.
Answer(s): (a) 9.10 a.m.; (b) 9.36 a.m.