Charlie and Vaidev started on a 35-km cycling trip at the same time. They cycled at the same speed for first 5 km. For the remaining 30 km, Charlie cycled faster than Vaidev. He arrived at the finishing point 20 minutes before Vaidev who was 5 km behind him. Vaidev did not change his speed throughout and completed it at 09 30.
- At what time did the trip begin? Give the answer in 12-hour format.
- What was Charlie's average speed for the remaining 30 km of the trip in km/h?
(a)
60 min = 1 h
20 min =
2060 h =
13 Vaidev's average speed
= 5 ÷
13 = 15 km/h
Time that Vaidev took for the trip
= 35 ÷ 15
= 2
515 h
= 2
13 h
= 2 h 20 min
2 h 20 min before 09 30 is 07 10.
(b)
To find the time that Charlie took for the remaining 30 km of the trip, we need to use the time that Vaidev took subtract that of the time taken for first 5 km and the time that Charlie was faster than Vaidev.
Time that Charlie took for the remaining 30 km of the trip
= 2
13 -
13 -
13 = 1
23 h
Charlie's average speed
= 30 ÷ 1
23 = 18 km/h
Answer(s): (a) 07 10; (b) 18 km/h