Question 662376
To solve all these types of problems,
add their rates of working to get their
rate working together
In words:
( 1 job / Sue's time to do the job ) + ( 1 job / Jim's time to do the job )
= ( 1 job / time for both working together )
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Let {{{ t }}} = time in hrs for both working together
Filling in the numbers:
{{{ 1/5 + 1/12 = 1/t }}}
Multiply both sides by {{{ 60t }}}
{{{ 12t + 5t = 60 }}}
{{{ 17t = 60 }}}
{{{ t = 60/17 }}}
Working together, they can do the job in about 3.53 hrs
or about 3 hrs 32 min