Nicole started jogging from the park to the reservoir at a speed of 114 m/min at 5 a.m. Her brother started jogging from the park later. They were beside each other at 5.35 a.m. and her brother reached the reservoir at 6 a.m. while Nicole was still 1900 m away. If both of them travelled at a constant speed throughout the journey, what time did her brother leave the park?
1 h = 60 min

From 5 a.m. to 6 a.m. = 1 h
From 5.35 a.m. to 6 a.m. = 25 min

Distance between the park and the reservoir
= 60 x 114 + 1900
= 6840 + 1900
= 8740 m

Distance that Nicole's brother had to cover to catch up with Nicole
= 35 x 114
= 3990 m

Distance that Nicole's brother travelled to the reservoir after catching up with Nicole
= 8740 - 3990
= 4750 m

Since Nicole's brother jogged 4750 m in 35 min,
Nicole's brother average speed
= 4750 ÷ 25
= 190 m/min

Duration that Nicole's brother took to jog to the reservoir
= 8740 ÷ 190
= 46 min

Time that Nicole's brother left the park:
46 min before 6 a.m. = 5.14 a.m.

Answer(s): 5.14 a.m.