PSLE
Molly and Mandy started jogging from the same point of the 8 km track round a lake. They started at the same time but in opposite directions. Molly jogged past Mandy after 5 km. Both of them did not change their speeds throughout. Molly took 30 min to complete one round. What was Mandy's jogging speed in m/min?
Distance that Mandy jogged when they passed each other
= 8 - 5
= 3 km

Time that Molly took to jog 8 km = 30 min

Time that Molly took to jog 1 km
= 30 ÷ 8
= 3.75 min

Time that Molly took to jog 5 km
= 5 x 3.75
= 18.75 min

When Molly took 18.75 min to jog 5 km, Mandy took the same time to jog 3 km.

1 km = 1000 m
3 km = 3000 m

Mandy's jogging speed
= 3000 ÷ 18.75
= 160 m/min

Answer(s): 160 m/min