Sel run around a track 3 times in 8 minutes. Mar run around the same track 2 times in 5 minutes.If sel and Mar begin at the same time and same place, what is the combined number of laps they both would have run when they next reach starting point at same time?

dgfgrafgdfge111 Nov 21, 2018

#3**+2 **

Sel runs 3/8 lap in one minute

Mar runs 2/5 lap in one minute

So.... Mar runs (2/5 - 3/8) = [ 16 - 15] / 40 = 1/40 of a lap farther than Sel does in one minute

So....in 40 minutes....they will be even again

In this time Sel runs (3/8)*40 = 15 laps

And Mar runs (2/5)*40 = 16 laps

So...combined.....they run 15 + 16 = 31 laps

CPhill Nov 21, 2018

#5**+2 **

3L/8min 2L/5min find(lowest) common denominator (40)

15L/40min 16L/40min At 40 minutes they will have combined 15+16 = 31 laps

(added 'lowest')

ElectricPavlov Nov 22, 2018