Peter and Tim took part in a 24 km marathon. Peter ran half the distance at a speed of 9 km/h and ran slower for the rest of the way at a speed of 5 km/h. Tim 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 4.30 a.m., at what time would each of them finish?
- Peter
- Tim
(a)
Half of the 24 km marathon = 24 ÷ 2 = 12 km
Time taken by Peter for the first half of the marathon
= 12 ÷ 9
= 1
13 h
Time taken by Peter for the last half of the marathon
= 12 ÷ 5
= 2
25 h
Total time taken by Peter
= 1
13 + 2
25= 3
1115 h
1 h = 60 min
1115 h =
1115 x 60 = 44 min
3
1115 h = 3 h 44 min
3 h 44 min after 4.30 a.m. = 8.14 a.m.
Time that Peter would finish the marathon = 8.14 a.m.
(b)
Time taken by Tim for the first half of the marathon
= 12 ÷ 10
= 1
15 h
Time taken by Tim for the last half of the marathon
= 12 ÷ 6
= 2 h
Total time taken by Tim
= 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 4.30 a.m. = 7.42 a.m.
Time that Tim would finish the marathon = 7.42 a.m.
Answer(s): (a) 8.14 a.m.; (b) 7.42 a.m.