PSLE
Vina and Phyllis started jogging from the same point of the 12 km track round a lake. They started at the same time but in opposite directions. Vina jogged past Phyllis after 10 km. Both of them did not change their speeds throughout. Vina took 15 min to complete one round. What was Phyllis's jogging speed in m/min?
Distance that Phyllis jogged when they passed each other
= 12 - 10
= 2 km

Time that Vina took to jog 12 km = 15 min

Time that Vina took to jog 1 km
= 15 ÷ 12
= 1.25 min

Time that Vina took to jog 10 km
= 10 x 1.25
= 12.5 min

When Vina took 12.5 min to jog 10 km, Phyllis took the same time to jog 2 km.

1 km = 1000 m
2 km = 2000 m

Phyllis's jogging speed
= 2000 ÷ 12.5
= 160 m/min

Answer(s): 160 m/min