Billy and Cole started on a 50-km cycling trip at the same time. They cycled at the same speed for first 5 km. For the remaining 45 km, Billy cycled faster than Cole. He arrived at the finishing point 20 minutes before Cole who was 5 km behind him. Cole 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 Billy's average speed for the remaining 45 km of the trip in km/h?
(a)
60 min = 1 h
20 min =
2060 h =
13 Cole's average speed
= 5 ÷
13 = 15 km/h
Time that Cole took for the trip
= 50 ÷ 15
= 3
515 h
= 3
13 h
= 3 h 20 min
3 h 20 min before 08 30 is 05 10.
(b)
To find the time that Billy took for the remaining 45 km of the trip, we need to use the time that Cole took subtract that of the time taken for first 5 km and the time that Billy was faster than Cole.
Time that Billy took for the remaining 45 km of the trip
= 3
13 -
13 -
13 = 2
23 h
Billy's average speed
= 45 ÷ 2
23 = 16
78 km/h
Answer(s): (a) 05 10; (b) 16
78 km/h