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

Time that Della took to jog 15 km = 15 min

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

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

When Della took 12 min to jog 12 km, Aria took the same time to jog 3 km.

1 km = 1000 m
3 km = 3000 m

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

Answer(s): 250 m/min