Distance and travel word problems

[joannamartinez]

It takes Rob 3 hours to do a job. It takes Tim 5 hours to do the same job. If Rob and Tim worked together, how long would it take them? Please advise. Thank you.

 

[wjm11]

Edited: I'll go with Galactus's approach.

 

[galactus]

You can find these problems if you do a search. They're old as time itself.

\(\displaystyle \frac{1}{3}+\frac{1}{5}=\frac{1}{t}\)

solve for t.

Or

\(\displaystyle \frac{t}{3}+\frac{t}{5}=1\)

solve for t.

Either way will result in the same solution.

 

[joannamartinez]

Ok. So what I did was add 3/r^1 + 5/r^2 which equals 3r+5/r^2. Is this correct? Please advise. Thank you.

 

[joannamartinez]

My last response is not correct. What I did was add 1/3 + 1/5 =1. 8x=15/8 which would be 1 hour and 53 minutes or 1.875 hours. Is this correct? Thank you.

 

[wjm11]

What I did was add 1/3 + 1/5 =1. 8x=15/8 which would be 1 hour and 53 minutes or 1.875 hours. Is this correct?

Yes.

 

[joannamartinez]

Thank you so very much for your help and patience. Have a great day!