Penelope started jogging from the church to the park at a speed of 115 m/min at 9 a.m. Her cousin started jogging from the church later. They were beside each other at 9.40 a.m. and her cousin reached the park at 10 a.m. while Penelope was still 1700 m away. If both of them travelled at a constant speed throughout the journey, what time did her cousin leave the church?
1 h = 60 min

From 9 a.m. to 10 a.m. = 1 h
From 9.40 a.m. to 10 a.m. = 20 min

Distance between the church and the park
= 60 x 115 + 1700
= 6900 + 1700
= 8600 m

Distance that Penelope's cousin had to cover to catch up with Penelope
= 40 x 115
= 4600 m

Distance that Penelope's cousin travelled to the park after catching up with Penelope
= 8600 - 4600
= 4000 m

Since Penelope's cousin jogged 4000 m in 40 min,
Penelope's cousin average speed
= 4000 ÷ 20
= 200 m/min

Duration that Penelope's cousin took to jog to the park
= 8600 ÷ 200
= 43 min

Time that Penelope's cousin left the church:
43 min before 10 a.m. = 9.17 a.m.

Answer(s): 9.17 a.m.