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# Sel run around a track 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

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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?

Nov 21, 2018
edited by dgfgrafgdfge111  Nov 21, 2018

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You left out the number of times that Sel ran around the track.....

Nov 21, 2018
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Sorry, its 3.

dgfgrafgdfge111  Nov 21, 2018
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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

Nov 21, 2018
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Thank you.

dgfgrafgdfge111  Nov 22, 2018
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3L/8min    2L/5min     find(lowest) common denominator  (40)

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