Warren and Eric took part in a 24 km marathon. Warren ran half the distance at a speed of 10 km/h and ran slower for the rest of the way at a speed of 8 km/h. Eric ran half his total time at 10 km/h and ran slower for the rest of the time at 6 km/h. If they started the marathon at 6.30 a.m., at what time would each of them finish?
- Warren
- Eric
(a)
Half of the 24 km marathon = 24 ÷ 2 = 12 km
Time taken by Warren for the first half of the marathon
= 12 ÷ 10
= 1
15 h
Time taken by Warren for the last half of the marathon
= 12 ÷ 8
= 1
12 h
Total time taken by Warren
= 1
15 + 1
12= 2
710 h
1 h = 60 min
710 h =
710 x 60 = 42 min
2
710 h = 2 h 42 min
2 h 42 min after 6.30 a.m. = 9.12 a.m.
Time that Warren would finish the marathon = 9.12 a.m.
(b)
Time taken by Eric for the first half of the marathon
= 12 ÷ 10
= 1
15 h
Time taken by Eric for the last half of the marathon
= 12 ÷ 6
= 2 h
Total time taken by Eric
= 1
15 + 2
= 3
15 h
1 h = 60 min
15 h =
15 x 60 = 12 min
3
15 h = 3 h 12 min
3 h 12 min after 6.30 a.m. = 9.42 a.m.
Time that Eric would finish the marathon = 9.42 a.m.
Answer(s): (a) 9.12 a.m.; (b) 9.42 a.m.