Simon and Elijah 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, Simon cycled faster than Elijah. He arrived at the finishing point 20 minutes before Elijah who was 5 km behind him. Elijah 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 Simon's average speed for the remaining 45 km of the trip in km/h?
(a)
60 min = 1 h
20 min =
2060 h =
13 Elijah's average speed
= 5 ÷
13 = 15 km/h
Time that Elijah took for the trip
= 50 ÷ 15
= 3
515 h
= 3
13 h
= 3 h 20 min
3 h 20 min before 07 30 is 04 10.
(b)
To find the time that Simon took for the remaining 45 km of the trip, we need to use the time that Elijah took subtract that of the time taken for first 5 km and the time that Simon was faster than Elijah.
Time that Simon took for the remaining 45 km of the trip
= 3
13 -
13 -
13 = 2
23 h
Simon's average speed
= 45 ÷ 2
23 = 16
78 km/h
Answer(s): (a) 04 10; (b) 16
78 km/h