Michael and Perry took part in a 32 km marathon. Michael ran half the distance at a speed of 10 km/h and ran slower for the rest of the way at a speed of 5 km/h. Perry ran half his total time at 12 km/h and ran slower for the rest of the time at 8 km/h. If they started the marathon at 4.30 a.m., at what time would each of them finish?
- Michael
- Perry
(a)
Half of the 32 km marathon = 32 ÷ 2 = 16 km
Time taken by Michael for the first half of the marathon
= 16 ÷ 10
= 1
35 h
Time taken by Michael for the last half of the marathon
= 16 ÷ 5
= 3
15 h
Total time taken by Michael
= 1
35 + 3
15= 4
45 h
1 h = 60 min
45 h =
45 x 60 = 48 min
4
45 h = 4 h 48 min
4 h 48 min after 4.30 a.m. = 9.18 a.m.
Time that Michael would finish the marathon = 9.18 a.m.
(b)
Time taken by Perry for the first half of the marathon
= 16 ÷ 12
= 1
13 h
Time taken by Perry for the last half of the marathon
= 16 ÷ 8
= 2 h
Total time taken by Perry
= 1
13 + 2
= 3
13 h
1 h = 60 min
13 h =
13 x 60 = 20 min
3
13 h = 3 h 20 min
3 h 20 min after 4.30 a.m. = 7.50 a.m.
Time that Perry would finish the marathon = 7.50 a.m.
Answer(s): (a) 9.18 a.m.; (b) 7.50 a.m.