PSLE
Jane and Mary started jogging from the same point of the 15 km track round a nature reserve. They started at the same time but in opposite directions. Jane jogged past Mary after 10 km. Both of them did not change their speeds throughout. Jane took 30 min to complete one round. What was Mary's jogging speed in m/min?
Distance that Mary jogged when they passed each other
= 15 - 10
= 5 km

Time that Jane took to jog 15 km = 30 min

Time that Jane took to jog 1 km
= 30 ÷ 15
= 2 min

Time that Jane took to jog 10 km
= 10 x 2
= 20 min

When Jane took 20 min to jog 10 km, Mary took the same time to jog 5 km.

1 km = 1000 m
5 km = 5000 m

Mary's jogging speed
= 5000 ÷ 20
= 250 m/min

Answer(s): 250 m/min