PSLE
Molly and Jane started jogging from the same point of the 12 km track round a housing estate. They started at the same time but in opposite directions. Molly jogged past Jane after 10 km. Both of them did not change their speeds throughout. Molly took 15 min to complete one round. What was Jane's jogging speed in m/min?
Distance that Jane jogged when they passed each other
= 12 - 10
= 2 km

Time that Molly took to jog 12 km = 15 min

Time that Molly took to jog 1 km
= 15 ÷ 12
= 1.25 min

Time that Molly took to jog 10 km
= 10 x 1.25
= 12.5 min

When Molly took 12.5 min to jog 10 km, Jane took the same time to jog 2 km.

1 km = 1000 m
2 km = 2000 m

Jane's jogging speed
= 2000 ÷ 12.5
= 160 m/min

Answer(s): 160 m/min