Emma started jogging from the bakery to the nature reserve at a speed of 96 m/min at 7 a.m. Her brother started jogging from the bakery later. They were beside each other at 7.35 a.m. and her brother reached the nature reserve at 8 a.m. while Emma was still 1600 m away. If both of them travelled at a constant speed throughout the journey, what time did her brother leave the bakery?
1 h = 60 min

From 7 a.m. to 8 a.m. = 1 h
From 7.35 a.m. to 8 a.m. = 25 min

Distance between the bakery and the nature reserve
= 60 x 96 + 1600
= 5760 + 1600
= 7360 m

Distance that Emma's brother had to cover to catch up with Emma
= 35 x 96
= 3360 m

Distance that Emma's brother travelled to the nature reserve after catching up with Emma
= 7360 - 3360
= 4000 m

Since Emma's brother jogged 4000 m in 35 min,
Emma's brother average speed
= 4000 ÷ 25
= 160 m/min

Duration that Emma's brother took to jog to the nature reserve
= 7360 ÷ 160
= 46 min

Time that Emma's brother left the bakery:
46 min before 8 a.m. = 7.14 a.m.

Answer(s): 7.14 a.m.