Question 600593
What part of the job does Alex get done in
2 hours?
Alex's rate of working is ( 1 fence ) / ( 8 hrs )
The fraction of the job done is {{{ (1/8)*2 = 1/4 }}}
There is 3/4 of the job left to do
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Add their rates of working to get their rate working together
{{{ 1/8 + 1/16 = (3/4)/t }}} ( where t is in hrs )
Multiply both sides by {{{ 4t }}}
{{{ t*( 4/8 + 4/16 ) = 3 }}}
Multiply both sides by {{{ 16 }}}
{{{ t*( 8 + 4 ) = 48 }}}
{{{ t = 48 / 12 }}}
{{{ t = 4 }}}
It will take both of them 4 hrs to complete the fence