Henry and Vincent took part in a 32 km marathon. Henry ran half the distance at a speed of 8 km/h and ran slower for the rest of the way at a speed of 6 km/h. Vincent ran half his total time at 10 km/h and ran slower for the rest of the time at 10 km/h. If they started the marathon at 3.30 a.m., at what time would each of them finish?
- Henry
- Vincent
(a)
Half of the 32 km marathon = 32 ÷ 2 = 16 km
Time taken by Henry for the first half of the marathon
= 16 ÷ 8
= 2 h
Time taken by Henry for the last half of the marathon
= 16 ÷ 6
= 2
23 h
Total time taken by Henry
= 2 + 2
23= 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 3.30 a.m. = 8.10 a.m.
Time that Henry would finish the marathon = 8.10 a.m.
(b)
Time taken by Vincent for the first half of the marathon
= 16 ÷ 10
= 1
35 h
Time taken by Vincent for the last half of the marathon
= 16 ÷ 10
= 1
35 h
Total time taken by Vincent
= 1
35 + 1
35 = 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 3.30 a.m. = 6.42 a.m.
Time that Vincent would finish the marathon = 6.42 a.m.
Answer(s): (a) 8.10 a.m.; (b) 6.42 a.m.