SOLUTION: three machines A , B and C take 3 hours to do a job, when working together. Suppose A and B are identical and that C working alone can complete the entire job in 12 hrs. How long w
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Question 234049: three machines A , B and C take 3 hours to do a job, when working together. Suppose A and B are identical and that C working alone can complete the entire job in 12 hrs. How long would it take A working alone to do the job?
a)4 hrs b) 8 hrs c)10 hrs d)12 hrs e) None of these
You can put this solution on YOUR website! three machines A , B and C take 3 hours to do a job, when working together.
Suppose A and B are identical and that C working alone can complete the entire job in 12 hrs.
How long would it take A working alone to do the job?
:
Let t = time for A or B working alone (Identical machines)
:
Let the completed job = 1
: + + = 1
: + = 1
Multiply equation by 12t, results
12(6) + 3t = 12t
:
72 = 12t - 3t
:
72 = 9t
t =
t = 8 hrs, A working alone
;
:
Check solution + + = + = 1
