SOLUTION: If 3 people can do a job in 20 hours how long would it take 4 people to do the same job. I tried a ratio: 3 is to 4 as 20 is to x (3/4 =20/x) = 60/4x divide each side by 4 and

Algebra ->  Rate-of-work-word-problems -> SOLUTION: If 3 people can do a job in 20 hours how long would it take 4 people to do the same job. I tried a ratio: 3 is to 4 as 20 is to x (3/4 =20/x) = 60/4x divide each side by 4 and      Log On


   

Question 489756: If 3 people can do a job in 20 hours how long would it take 4 people to do the same job.
I tried a ratio: 3 is to 4 as 20 is to x (3/4 =20/x) = 60/4x divide each side by 4 and x is 15. Am I on the right track?
Found 2 solutions by chessace, Gogonati:
Answer by chessace(471) About Me  (Show Source):
You can put this solution on YOUR website!
Not really. Almost every step you took is wrong, and then you wrote down the right answer for no apparant reason.
Job takes 3 * 20 man-hours = 60
Divide by 4 people to get 15 (you sort of figured that part out, but didn't express the steps right.
4 x = 3 * 20 with units labeled would be a better start.

Answer by Gogonati(855) About Me  (Show Source):
You can put this solution on YOUR website!
You are on the right track because the quantities in this problem are into inverse proportion.
x*y=k<=>k=20*3=60, and 4*x=60<=> x=15.