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

Time that Sophia took to jog 15 km = 30 min

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

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

When Sophia took 20 min to jog 10 km, Sonia took the same time to jog 5 km.

1 km = 1000 m
5 km = 5000 m

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

Answer(s): 250 m/min