Julian and Zeph started on a 55-km cycling trip at the same time. They cycled at the same speed for first 5 km. For the remaining 50 km, Julian cycled faster than Zeph. He arrived at the finishing point 12 minutes before Zeph who was 5 km behind him. Zeph did not change his speed throughout and completed it at 08 30.
- At what time did the trip begin? Give the answer in 12-hour format.
- What was Julian's average speed for the remaining 50 km of the trip in km/h?
(a)
60 min = 1 h
12 min =
1260 h =
15 Zeph's average speed
= 5 ÷
15 = 25 km/h
Time that Zeph took for the trip
= 55 ÷ 25
= 2
525 h
= 2
15 h
= 2 h 12 min
2 h 12 min before 08 30 is 06 18.
(b)
To find the time that Julian took for the remaining 50 km of the trip, we need to use the time that Zeph took subtract that of the time taken for first 5 km and the time that Julian was faster than Zeph.
Time that Julian took for the remaining 50 km of the trip
= 2
15 -
15 -
15 = 1
45 h
Julian's average speed
= 50 ÷ 1
45 = 27
79 km/h
Answer(s): (a) 06 18; (b) 27
79 km/h