Work Problems

1
Work Problems

• Objectives
• Write equations for work problems
• Solve the equations for valid solutions

2
Use the following equation

• (work rate) x (time) (work done)
• Work rate means the fractional part of a job done
  in a given amount of time
• Work done should always be one job unless
  otherwise stated.

3
The Question

• One printing press can finish a job in 8 hours.
  The same job would take a second press 12 hours.
  How long would it take both presses working
  together?

4
The setup
Note1 work rate is equal to jobs per unit of time
Note2 To setup the equations the two machines
working together will complete 1 job. So, work
done by press1 combined with the work done by
press2 will be 1 job in total.
5
Problem 2

• An installer can carpet a room in 3 hours. An
  assistant takes 4.5 hours to do the same job. If
  the assistant helps for 1 hour and then is called
  away, how long will it take the installer to
  finish.

6
The setup
n1
1
7
Problem 3

• Phil can paint the garage in 12 hours, Rick can
  do it in 10 hours. They work together for 3
  hours then Phil leaves. How long will it take
  Rick to finish the job alone?

8
The setup
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Problem 4

• Chuck can shovel the snow off his driveway in 40
  minutes. He shovels for 20 minutes and then is
  joined by Joan. If they shovel the remaining
  snow in 10 minutes. How long would it take Joan
  to shovel alone?