Oliver and Daniel took part in a 42 km marathon. Oliver 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. Daniel 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 3.30 a.m., at what time would each of them finish?

1. Oliver
2. Daniel

(a)
Half of the 42 km marathon = 42 ÷ 2 = 21 km

Time taken by Oliver for the first half of the marathon
= 21 ÷ 9
= 2¹₃ h

Time taken by Oliver for the last half of the marathon
= 21 ÷ 9
= 2¹₃ h

Total time taken by Oliver
= 2¹₃ + 2¹₃
= 4²₃ h

1 h = 60 min
²₃ h = ²₃ x 60 = 40 min
4²₃ h = 4 h 40 min

4 h 40 min after 3.30 a.m. = 8.10 a.m.
Time that Oliver would finish the marathon = 8.10 a.m.

(b)
Time taken by Daniel for the first half of the marathon
= 21 ÷ 10
= 2¹₁₀ h

Time taken by Daniel for the last half of the marathon
= 21 ÷ 7
= 3 h

Total time taken by Daniel
= 2¹₁₀ + 3
= 5¹₁₀ h

1 h = 60 min
¹₁₀ h = ¹₁₀ x 60 = 6 min
5¹₁₀ h = 5 h 6 min
5 h 6 min after 3.30 a.m. = 8.36 a.m.
Time that Daniel would finish the marathon = 8.36 a.m.

Answer(s): (a) 8.10 a.m.; (b) 8.36 a.m.