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?

Correct result:

x =  2 d

Solution:

$$\begin{gathered} d_1={\displaystyle \frac{1}{5}}+{\displaystyle \frac{1}{6}}+{\displaystyle \frac{1}{7.5}}={\displaystyle \frac{1}{2}}=0.5 \\ x={\displaystyle \frac{1}{d_1}}={\displaystyle \frac{1}{0.5}}=2\text{ d} \end{gathered}$$

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Showing 2 comments:

Nestor

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

2 years ago  Like

Dr Math

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

2 years ago  Like

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