Question

Tom and Becky can paint Jim's fence together in 12 hours. If all people paint at the same rate, how many hours would it take to paint the fence if Huck joins Tom and Becky, and all three of them paint Jim's fence together?

Answer 1

Answer: 8 hours

Step-by-step explanation:

Let x be the time taken by each person to paint the fence.

Given: Tom and Becky can paint Jim's fence together in 12 hours.

Since all people paint at the same rate, then we have the following equation ;-

$\dfrac{1}{x}+\dfrac{1}{x}=\dfrac{1}{12}\\\\\Rightarrow\ \dfrac{2}{x}=\dfrac{1}{12}\\\\\Rightarrow\ x=24$

Thus, the time taken by each person to paint the fence alone = 24 hours

Now, the time taken by all three paint together:-

$\dfrac{1}{t}=\dfrac{1}{24}+\dfrac{1}{24}+\dfrac{1}{24}\\\\\Rightarrow\ \dfrac{1}{t}=\dfrac{3}{24}\\\\\Rightarrow\ t=\dfrac{24}{3}=8\text{ hours}$

Hence, it would take 8 hours if all three paint together.