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)   (Show Source): You can put this solution on YOUR website!
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)   (Show Source): You can put this solution on YOUR website!
.
The first man makes  of the job per hour.


The second makes  of the job per hour.


The third man makes  of the job per hour.


The three man working together make  of the job per hour,


    which is  =  of the job per hour.



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