Ian and Luke started on a 48-km cycling trip at the same time. They cycled at the same speed for first 5 km. For the remaining 43 km, Ian cycled faster than Luke. He arrived at the finishing point 20 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 Ian's average speed for the remaining 43 km of the trip in km/h?
(a)
60 min = 1 h
20 min =
2060 h =
13 Luke's average speed
= 5 ÷
13 = 15 km/h
Time that Luke took for the trip
= 48 ÷ 15
= 3
315 h
= 3
15 h
= 3 h 12 min
3 h 12 min before 08 30 is 05 18.
(b)
To find the time that Ian took for the remaining 43 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 Ian was faster than Luke.
Time that Ian took for the remaining 43 km of the trip
= 3
15 -
13 -
13 = 2
815 h
Ian's average speed
= 43 ÷ 2
815 = 16
3738 km/h
Answer(s): (a) 05 18; (b) 16
3738 km/h