Yoko started jogging from the market to the nature reserve at a speed of 108 m/min at 8 a.m. Her cousin started jogging from the market later. They were beside each other at 8.35 a.m. and her cousin reached the nature reserve at 9 a.m. while Yoko was still 1800 m away. If both of them travelled at a constant speed throughout the journey, what time did her cousin leave the market?
1 h = 60 min

From 8 a.m. to 9 a.m. = 1 h
From 8.35 a.m. to 9 a.m. = 25 min

Distance between the market and the nature reserve
= 60 x 108 + 1800
= 6480 + 1800
= 8280 m

Distance that Yoko's cousin had to cover to catch up with Yoko
= 35 x 108
= 3780 m

Distance that Yoko's cousin travelled to the nature reserve after catching up with Yoko
= 8280 - 3780
= 4500 m

Since Yoko's cousin jogged 4500 m in 35 min,
Yoko's cousin average speed
= 4500 ÷ 25
= 180 m/min

Duration that Yoko's cousin took to jog to the nature reserve
= 8280 ÷ 180
= 46 min

Time that Yoko's cousin left the market:
46 min before 9 a.m. = 8.14 a.m.

Answer(s): 8.14 a.m.