PSLE
Chloe and Mary started jogging from the same point of the 15 km track round a housing estate. They started at the same time but in opposite directions. Chloe jogged past Mary after 12 km. Both of them did not change their speeds throughout. Chloe took 15 min to complete one round. What was Mary's jogging speed in m/min?
Distance that Mary jogged when they passed each other
= 15 - 12
= 3 km

Time that Chloe took to jog 15 km = 15 min

Time that Chloe took to jog 1 km
= 15 ÷ 15
= 1 min

Time that Chloe took to jog 12 km
= 12 x 1
= 12 min

When Chloe took 12 min to jog 12 km, Mary took the same time to jog 3 km.

1 km = 1000 m
3 km = 3000 m

Mary's jogging speed
= 3000 ÷ 12
= 250 m/min

Answer(s): 250 m/min