Kimberly started jogging from the bank to the reservoir at a speed of 110 m/min at 9 a.m. Her cousin started jogging from the bank later. They were beside each other at 9.32 a.m. and her cousin reached the reservoir at 10 a.m. while Kimberly was still 1400 m away. If both of them travelled at a constant speed throughout the journey, what time did her cousin leave the bank?
1 h = 60 min

From 9 a.m. to 10 a.m. = 1 h
From 9.32 a.m. to 10 a.m. = 28 min

Distance between the bank and the reservoir
= 60 x 110 + 1400
= 6600 + 1400
= 8000 m

Distance that Kimberly's cousin had to cover to catch up with Kimberly
= 32 x 110
= 3520 m

Distance that Kimberly's cousin travelled to the reservoir after catching up with Kimberly
= 8000 - 3520
= 4480 m

Since Kimberly's cousin jogged 4480 m in 32 min,
Kimberly's cousin average speed
= 4480 ÷ 28
= 160 m/min

Duration that Kimberly's cousin took to jog to the reservoir
= 8000 ÷ 160
= 50 min

Time that Kimberly's cousin left the bank:
50 min before 10 a.m. = 9.10 a.m.

Answer(s): 9.10 a.m.