SOLUTION: If steven can mix 20 drinks in 5 minutes, Sue can mix 20 drinks in 10 minutes, Jack can mix 20 drinks in 15 minutes, how much time will it take all 3 of them working together to mi

Algebra ->  Complex Numbers Imaginary Numbers Solvers and Lesson -> SOLUTION: If steven can mix 20 drinks in 5 minutes, Sue can mix 20 drinks in 10 minutes, Jack can mix 20 drinks in 15 minutes, how much time will it take all 3 of them working together to mi      Log On


   

Question 299295: If steven can mix 20 drinks in 5 minutes, Sue can mix 20 drinks in 10 minutes, Jack can mix 20 drinks in 15 minutes, how much time will it take all 3 of them working together to mix the 20 drinks? Please, give me the explaination.
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
First find the rate (job/minute) at which each person can work. The job for each of them is to mix 20 drinks.
If Steven can do the job in 5 minutes, he can do 1%2F5 of the job in 1 minute.
If SUe can do the job in 10 minutes, she can do 1%2F10 of the job in 1 minute.
If Jack can do the job in 15 minutes, he can do 1%2F15 of the job in 1 minute.
Working together, they can do 1%2F5%2B1%2F10%2B1%2F15+=+11%2F30 of the job in 1 minute.
So it will take them 30%2F11minutes working together.
30%2F11+=+2.73minutes or 2 minutes and 43.64 seconds.