PSLE
Elsa and Anna started jogging from the same point of the 12 km track round a park. They started at the same time but in opposite directions. Elsa jogged past Anna after 10 km. Both of them did not change their speeds throughout. Elsa 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
= 12 - 10
= 2 km

Time that Elsa took to jog 12 km = 15 min

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

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

When Elsa took 12.5 min to jog 10 km, Anna took the same time to jog 2 km.

1 km = 1000 m
2 km = 2000 m

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

Answer(s): 160 m/min