PSLE
Ginny and Lily 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. Ginny jogged past Lily after 12 km. Both of them did not change their speeds throughout. Ginny took 15 min to complete one round. What was Lily's jogging speed in m/min?
Distance that Lily jogged when they passed each other
= 15 - 12
= 3 km

Time that Ginny took to jog 15 km = 15 min

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

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

When Ginny took 12 min to jog 12 km, Lily took the same time to jog 3 km.

1 km = 1000 m
3 km = 3000 m

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

Answer(s): 250 m/min