Question 1013760
What fraction of the job did Max
get done in 2 hrs?
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Max's rate of working:
[ 1 machine repaired ] / [ 4 hrs ] = {{{ 1/4 }}}
Fraction of job done in 2 hrs:
{{{ ( 1/4 )*2 = 1/2 }}}
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There is {{{ 1 - 1/2 = 1/2 }}} of the job left to do
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Let {{{ t }}} = time in hrs for them to finish job working together
Add their rates of working to get their rate working together
{{{ 1/4 + 1/8 = (( 1/2)) / t }}}
Multiply both sides by {{{ 8t }}}
{{{ 2t + t = 4 }}}
{{{ 3t = 4 }}}
{{{ t = 4/3 }}} hrs
It took them 4/3 hrs = 1 hr and 20 min to finish
the job working together