SOLUTION: Three men can individually do a job in 5 ,6 and 7 hours respectively,, what fractions of the entire job is done by the three man together in 1 hour ?

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Question 1096227: Three men can individually do a job in 5 ,6 and 7 hours respectively,, what fractions of the entire job is done by the three man together in 1 hour ?
Found 2 solutions by Edwin McCravy, ikleyn:
Answer by Edwin McCravy(20054) About Me  (Show Source):
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The first man can do a job in 5 hours, 
so in 1 hour he can do 1/5th of the job.

The second man can do a job in 6 hours, 
so in 1 hour he can do 1/6th of the job.

The third man can do a job in 7 hours, 
so in 1 hour he can do 1/7th of the job.

So add the fractions 1/5 + 1/6 + 1/7 = ???

Hint: get a LCD of 5󬝳 which is 210.

1/5 + 1/6 + 1/7 = ?/210 + ?/210 + ?/210 = ?/210

Edwin

Answer by ikleyn(52780) About Me  (Show Source):
You can put this solution on YOUR website!
.
The first man makes 1%2F5 of the job per hour.


The second makes 1%2F6 of the job per hour.


The third man makes 1%2F7 of the job per hour.


The three man working together make 1%2F5+%2B+1%2F6+%2B+1%2F7 of the job per hour,


    which is %286%2A7%29%2F210%2B+%285%2A7%29%2F210+%2B+%285%2A6%29%2F210 = 107%2F210 of the job per hour.