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 t

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Question 112784: 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 ankor@dixie-net.com(22740) About Me  (Show Source):
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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?
:
The completed job is the mixing of 20 drinks.
Let the completed job = 1
:
Let t = time required when working together:
:
t%2F5 + t%2F10 + t%2F15 = 1
:
Multiply the equation by 30 to get rid of those annoying denominators:
30*t%2F5 + 30*t%2F10 + 30*t%2F15 = 30(1)
:
Cancel them denominators and you have:
6t + 3t + 2t = 30
11t = 30
t = 30%2F11
t = 2.73 minutes for all three to mix 20 drinks
:
Convert the decimal portion to seconds: .73 * 60 = 43.6 seconds
2 min 43.6 sec