If a plumber bills $75/hour, how much does he make every second? How much does he make per year? Assume he works 50 hours per week, 48 weeks per year

Question

how do i start

 

Answer 1

In order to change the units without changing the value, we use the Multiplicative Identity (that is, 1).

 

This problem gives  (choose the appropriate expression):

    1  =  (60 seconds) / (1 minute)  =  (1 minute) / (60 seconds)

    1  =  (60 minutes) / (1 hour)  =  (1 hour) / (60 minutes)

    1  =  (50 hours) / (1 week)  =  (1 week) / (50 hours)

    1  =  (48 weeks)/(1 year)  =  (1 year) / (48 weeks)

 

The plumber earns:

          $75 / hour

      ( ($75)/(1 hour) ) * 1

      ( ($75)/(1 hour) )*( (1 hour)/(60 minutes) )*( (1 minute)/(60 seconds) )

        (75/1)*(1/60)*(1/60) $/second       [note: hours and minutes cancel out]

       $0.02/second      [2 cents per second, or $1.20 per minute

                       -- don't waste money talking to him/her]

    ( ($75)/(1 hour) )*( (50 hours)/(1 week) )*( (48 weeks)/(1 year) )

       (75/1)*(50/1)*(48/1)  $/year

         $180,000/year

 

TMI:  As a "rule of thumb," if someone is paid $75/hr, they make a little more than $150,000/year (multiply by 2000 -- this assumes working 2080 hours, or 52 weeks of 40 hr/week).  Here, it is 48 weeks at 50 hours/week, so multiply by 2400 to be exact.