Module 12: Work Problems

Question 1

Work =

Answer 1

Rate * Time

Question 2

Time =

Answer 2

Work / Rate

Question 3

Rate =

Answer 3

Work / Time

Question 4

Three ways that work is presented:

Answer 4

1) A specific quantity of work in a specific amount of time.
Ex: Jackie can paint 20 fences in 4 weeks. (rate: 20/4 = 5 fences / 1 week)

2) A single job completed in a specific amount of time
Ex: Tom can mow the lawn in 45 minutes. (rate: 1 lawn / 45 minutes)

3) A fractional amount of work is completed in a specific amount of time.
Ex: A machine can finish 1/4 of a job in 2 hours. (1/4 job / 2 hours -> 1/4 * 1/2 = 1 job/ 8 hrs

Question 5

When two objects are working together to complete a task, I will

Answer 5

add the rates of each object to find the combined rate

Question 6

Find % of task completed by one object - 3 steps

Answer 6

1) Calculate rate of each item
2) Calculate combined rate by adding all individual rates together
3) Calculate % of task completed: (rate of object in question / rate of whole team)

Question 7

When two objects are working in opposition, I will

Answer 7

subtract the rates to find the true combined rate of progress

Question 8

In relative work problems, where one worker’s rate is given in the form of another worker’s rate (percentage, fraction, add/subtract from, etc), I will

Answer 8

calculate R x T for each to find each individual work contribution, then add the works together to help find the answer. This will usually be the easiest way.