Lee and Liam 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, Lee cycled faster than Liam. He arrived at the finishing point 12 minutes before Liam who was 5 km behind him. Liam did not change his speed throughout and completed it at 08 25.
- At what time did the trip begin? Give the answer in 12-hour format.
- What was Lee's average speed for the remaining 50 km of the trip in km/h?
(a)
60 min = 1 h
12 min =
1260 h =
15 Liam's average speed
= 5 ÷
15 = 25 km/h
Time that Liam took for the trip
= 55 ÷ 25
= 2
525 h
= 2
15 h
= 2 h 12 min
2 h 12 min before 08 25 is 06 13.
(b)
To find the time that Lee took for the remaining 50 km of the trip, we need to use the time that Liam took subtract that of the time taken for first 5 km and the time that Lee was faster than Liam.
Time that Lee took for the remaining 50 km of the trip
= 2
15 -
15 -
15 = 1
45 h
Lee's average speed
= 50 ÷ 1
45 = 27
79 km/h
Answer(s): (a) 06 13; (b) 27
79 km/h