Andy and Jeremy started on a 48-km cycling trip at the same time. They cycled at the same speed for first 5 km. For the remaining 43 km, Andy cycled faster than Jeremy. He arrived at the finishing point 20 minutes before Jeremy who was 5 km behind him. Jeremy did not change his speed throughout and completed it at 08 25.

1. At what time did the trip begin? Give the answer in 12-hour format.
2. What was Andy's average speed for the remaining 43 km of the trip in km/h?

(a)
60 min = 1 h
20 min =²⁰₆₀ h = ¹₃ 

Jeremy's average speed
= 5 ÷ ¹₃
= 15 km/h

Time that Jeremy took for the trip
= 48 ÷ 15
= 3³₁₅ h
= 3¹₅ h
= 3 h 12 min

3 h 12 min before 08 25 is 05 13.

(b)
To find the time that Andy took for the remaining 43 km of the trip, we need to use the time that Jeremy took subtract that of the time taken for first 5 km and the time that Andy was faster than Jeremy.

Time that Andy took for the remaining 43 km of the trip
= 3¹₅ - ¹₃ - ¹₃
= 2⁸₁₅ h

Andy's average speed
= 43 ÷ 2⁸₁₅
= 16³⁷₃₈ km/h

Answer(s): (a) 05 13; (b) 16³⁷₃₈ km/h