Question 892418
Ad their rates of working
Mandy's rate:
( 1 project ) / ( 7 hrs )
Colin's rate:
( 1 project ) / ( 3 hrs )
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Let {{{ t }}} = time to finish project
if they work together
{{{ 1/7 + 1/3 = 1/t }}}
Multiply both sides by {{{ 21t }}}
{{{ 3t + 7t = 21 }}}
{{{ 10t = 21 }}}
{{{ t = 2.1 }}} hrs
Convert {{{ .1 }}} hrs to min
{{{ .1*60 = 6 }}} min
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Working together, it will take
them 2 hrs and 6 min