QR Question

[juswanthatDDS]

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These questions come up all the time and i know there simple but what is best and quickest way to go through them

Justin paints fence in 5 hours, austin paints it in 2 hours, gustin paints it in 2.5 hours, how long will it take for all three of them working together?

50 mins

55 mins

45 mins

1 hours 5 mins

1 hour 10 mins

 

[Illfavor]

Quickest way is to add their rates. Find LCD, and just add. Make sure the units are in houses/hours then you can flip it over to make it hours/house...and you're done.

 

[jHoon]

1/5 + 1/2 + 1/2.5 = 1/T

solve for T and viola!

 

[trocha86]

what was the answer?

 

[jHoon]

should be about 55 minutes