Zeph and Luke 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, Zeph cycled faster than Luke. He arrived at the finishing point 12 minutes before Luke who was 5 km behind him. Luke 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 Zeph's average speed for the remaining 50 km of the trip in km/h?
(a)
60 min = 1 h
12 min =
1260 h =
15 Luke's average speed
= 5 ÷
15 = 25 km/h
Time that Luke 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 Zeph took for the remaining 50 km of the trip, we need to use the time that Luke took subtract that of the time taken for first 5 km and the time that Zeph was faster than Luke.
Time that Zeph took for the remaining 50 km of the trip
= 2
15 -
15 -
15 = 1
45 h
Zeph's average speed
= 50 ÷ 1
45 = 27
79 km/h
Answer(s): (a) 06 18; (b) 27
79 km/h