Three painters

The three painters have painted bridge. The first would work done in 5 days, the second in 6 days, and the third in 7.5 days. How long will the bridge work if they work together?

Result

x =  2 d

Solution:

$d_{1}=\dfrac{ 1 }{ 5 } +\dfrac{ 1 }{ 6 } + \dfrac{ 1 }{ 7.5 }=\dfrac{ 1 }{ 2 }=0.5 \ \\ \ \\ x=\dfrac{ 1 }{ d_{1} }=\dfrac{ 1 }{ 0.5 }=2 \ \text{d}$

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Leave us a comment of this math problem and its solution (i.e. if it is still somewhat unclear...):

Showing 2 comments:

Nestor

Why the third fraction 1/7.5 when it is supposed to be 1/7?

1 year ago  Like

Dr Math

Yes, there was bug, but now is corrected. Thank you

1 year ago  Like

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