Question 1157207
The rate of working for the crew of 2 is:
[ 1 siding job ] / [ 30 hrs ]
The rate of working for the crew of 3 is:
[ 1 siding job ] / [ 24 hrs ]
Add their rates to get rate working together
Let {{{ t }}} = time in hrs for both crews to
do the job
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{{{ 1/30 + 1/24 = 1/t }}}
multiply both sides by {{{ 120t }}}
{{{ 4t + 5t = 120 }}}
{{{ 9t = 120 }}}
{{{ t = 13.333 }}}
{{{ .333*60 = 20 }}}
All 5 working together take 13 hrs 20 min
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{{{ .0333 + .041667 = 1/t }}}
{{{ .075 = 9/120 }}}
{{{ .075 = .075 }}}
OK