Ben and Nick started on a 50-km cycling trip at the same time. They cycled at the same speed for first 10 km. For the remaining 40 km, Ben cycled faster than Nick. He arrived at the finishing point 40 minutes before Nick who was 10 km behind him. Nick did not change his speed throughout and completed it at 07 30.

1. At what time did the trip begin? Give the answer in 12-hour format.
2. What was Ben's average speed for the remaining 40 km of the trip in km/h?

(a)
60 min = 1 h
40 min =⁴⁰₆₀ h = ²₃ 

Nick's average speed
= 10 ÷ ²₃
= 15 km/h

Time that Nick took for the trip
= 50 ÷ 15
= 3⁵₁₅ h
= 3¹₃ h
= 3 h 20 min

3 h 20 min before 07 30 is 04 10.

(b)
To find the time that Ben took for the remaining 40 km of the trip, we need to use the time that Nick took subtract that of the time taken for first 10 km and the time that Ben was faster than Nick.

Time that Ben took for the remaining 40 km of the trip
= 3¹₃ - ²₃ - ²₃
= 2 h

Ben's average speed
= 40 ÷ 2
= 20 km/h

Answer(s): (a) 04 10; (b) 20 km/h