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

Algebra ->  Rate-of-work-word-problems -> SOLUTION: If Steven can mix 20 drinks in 5 minutes, Sue can mix 20 drinks in 10 minutes and Jack can mix 20 drinks in 15 minutes, how much time will it take all 3 of them working together to      Log On


   

Question 285456: If Steven can mix 20 drinks in 5 minutes, Sue can mix 20 drinks in 10 minutes and 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?
Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
in the combined time (x), they each mix a FRACTION of the 20 total drinks

Steve mixes ___ x/5

Sue mixes ___ x/10

Jack mixes ___ x/15

the fractions sum to one (the whole)

(x / 5) + (x / 10) + (x / 15) = 1

6x + 3x + 2x = 30 ___ x = 30/11


this is a mathematical solution; since each person would most likely mix a whole number of drinks (not 2/3 of a drink),
the number is a good approximation to REALITY