PSLE
Anna and Erny 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. Anna jogged past Erny after 10 km. Both of them did not change their speeds throughout. Anna took 30 min to complete one round. What was Erny's jogging speed in m/min?
Distance that Erny jogged when they passed each other
= 15 - 10
= 5 km

Time that Anna took to jog 15 km = 30 min

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

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

When Anna took 20 min to jog 10 km, Erny took the same time to jog 5 km.

1 km = 1000 m
5 km = 5000 m

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

Answer(s): 250 m/min