PSLE
Penny and Elsa started jogging from the same point of the 15 km track round a lake. They started at the same time but in opposite directions. Penny jogged past Elsa after 12 km. Both of them did not change their speeds throughout. Penny took 30 min to complete one round. What was Elsa's jogging speed in m/min?
Distance that Elsa jogged when they passed each other
= 15 - 12
= 3 km

Time that Penny took to jog 15 km = 30 min

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

Time that Penny took to jog 12 km
= 12 x 2
= 24 min

When Penny took 24 min to jog 12 km, Elsa took the same time to jog 3 km.

1 km = 1000 m
3 km = 3000 m

Elsa's jogging speed
= 3000 ÷ 24
= 125 m/min

Answer(s): 125 m/min