Victoria started jogging from the cafe to the garden at a speed of 96 m/min at 9 a.m. Her sister started jogging from the cafe later. They were beside each other at 9.35 a.m. and her sister reached the garden at 10 a.m. while Victoria was still 1600 m away. If both of them travelled at a constant speed throughout the journey, what time did her sister leave the cafe?
1 h = 60 min

From 9 a.m. to 10 a.m. = 1 h
From 9.35 a.m. to 10 a.m. = 25 min

Distance between the cafe and the garden
= 60 x 96 + 1600
= 5760 + 1600
= 7360 m

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

Distance that Victoria's sister travelled to the garden after catching up with Victoria
= 7360 - 3360
= 4000 m

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

Duration that Victoria's sister took to jog to the garden
= 7360 ÷ 160
= 46 min

Time that Victoria's sister left the cafe:
46 min before 10 a.m. = 9.14 a.m.

Answer(s): 9.14 a.m.