Elijah and Liam started on a 45-km cycling trip at the same time. They cycled at the same speed for first 10 km. For the remaining 35 km, Elijah cycled faster than Liam. He arrived at the finishing point 30 minutes before Liam who was 10 km behind him. Liam did not change his speed throughout and completed it at 07 30.
- At what time did the trip begin? Give the answer in 12-hour format.
- What was Elijah's average speed for the remaining 35 km of the trip in km/h?
(a)
60 min = 1 h
30 min =
3060 h =
12 Liam's average speed
= 10 ÷
12 = 20 km/h
Time that Liam took for the trip
= 45 ÷ 20
= 2
520 h
= 2
14 h
= 2 h 15 min
2 h 15 min before 07 30 is 05 15.
(b)
To find the time that Elijah took for the remaining 35 km of the trip, we need to use the time that Liam took subtract that of the time taken for first 10 km and the time that Elijah was faster than Liam.
Time that Elijah took for the remaining 35 km of the trip
= 2
14 -
12 -
12 = 1
14 h
Elijah's average speed
= 35 ÷ 1
14 = 28 km/h
Answer(s): (a) 05 15; (b) 28 km/h