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

Time that Molly took to jog 15 km = 15 min

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

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

When Molly took 12 min to jog 12 km, Anna took the same time to jog 3 km.

1 km = 1000 m
3 km = 3000 m

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

Answer(s): 250 m/min