Question 747757
I can do part 3), I think.
Their rates of working are:
Woman:
( 1 job ) / ( 10 hrs )
daughter:
( 1 job ) / ( 12 hrs )
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Find the fraction of the job that woman and
daughter get done in 1 hr.
woman:
( 1 job / 10 hrs ) x ( 1 hr ) = ( 1/10 ) job
daughter:
( 1 job / 12 hrs ) x ( 1 hr ) = ( 1/12 ) job
So, in 1 hr, working together they did
{{{ 1/10 + 1/12 = 6/60 + 5/60 = 11/60 }}} job
That means there was {{{ 60/60 - 11/60 = 49/60 }}}
of the job left to do
Let {{{x}}} = hrs worked by woman alone
{{{ x/10 }}} is the fraction of the remainder
of the job she gets done
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{{{ 11/60 }}} of the job is already done
I can say:
{{{ 1/10 = ( 49/60 )/ x }}}
{{{ x = 490/60 }}} hrs
{{{ ( 490/60 )*60 = 490 }}} min
x = 8 hrs and 10 min
Hope I got it