Question 301967
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? 
--------
Steven Data:
time = 5 minutes/job ; rate = 1/5 job/min
============
Sue Data:
time = 10 min/job ; rate = 1/10 job/min
============
Jack Data:
time = 15 min/job ; rate = 1/15 job/min
============
Together Data:
time = x min/job ; rate = 1/x job/min
==========================================
Equation:
rate + rate + rate = together rate
1/5 + 1/10 + 1/15 = 1/x
---------------------------
Multiply thru by 30x to get:
6x + 3x + 2x = 30
11x = 30
x = 30/11 = 2.73 minutes to mix 20 drinks
============================================
Cheers,
Stan H.
============================================