Question 40410
A tank can be filled in 18 hours by Pipe A or 24 hours by Pipe B. How long would it take both pipes to fill the tank?
_____hours
Pipe A's rate: (1/18)
Pipe B's rate: (1/24)
Rate * Time = Work
(t/18) + (t/24) = 1
72(t/18) + 72(t/24) = 72
4t + 3t = 72
7t = 72
t = 72/7 = 10 2/7
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It takes Sarah 8 hours to fill a Widget. Jerry can do the same job in 12 hours. How long would it take them to assemble a Widget if they worked together?
_______hours
Sarah's rate: (1/8)
Jerry's rate: (1/12)
RATE * TIME = WORK
(t/8) + (t/12) = 1
24(t/8) + 24(t/12) = 24
3t + 2t = 24
5t = 24
t = 24/5 = 4 4/5