Ben and Henry started on a 60-km cycling trip at the same time. They cycled at the same speed for first 12 km. For the remaining 48 km, Ben cycled faster than Henry. He arrived at the finishing point 40 minutes before Henry who was 12 km behind him. Henry did not change his speed throughout and completed it at 09 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 48 km of the trip in km/h?

(a)
60 min = 1 h
40 min =⁴⁰₆₀ h = ²₃ 

Henry's average speed
= 12 ÷ ²₃
= 18 km/h

Time that Henry took for the trip
= 60 ÷ 18
= 3⁶₁₈ h
= 3¹₃ h
= 3 h 20 min

3 h 20 min before 09 30 is 06 10.

(b)
To find the time that Ben took for the remaining 48 km of the trip, we need to use the time that Henry took subtract that of the time taken for first 12 km and the time that Ben was faster than Henry.

Time that Ben took for the remaining 48 km of the trip
= 3¹₃ - ²₃ - ²₃
= 2 h

Ben's average speed
= 48 ÷ 2
= 24 km/h

Answer(s): (a) 06 10; (b) 24 km/h