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Online Quiz (Worksheet A B C D)

Questions Per Quiz = 2 4 6 8 10

Grade 8 - Mathematics
9.39 Word Problems on Work

Example:
Method :
  • Write or get the algebraic equation.
  • Solve for the unknown.
Question: Two people can work a task in 5 hours. If the first person can complete the task alone in 9 hours. How long would it take the second person to complete the same task working alone.
Solution:
Total time in hoursFractional part of the job done in 1 hour
First Person91/9
Second Personx1/x
Together51/5

The first person takes 9 hours to complete the task working alone, implies the person completes 1/9th of the job in each hour.
Let x be the hours it takes second person to complete the task working alone, implies that the person takes 1/x of the job each hour.
Working together it takes the two people to complete the job in 5 hours. That means that each hour 1/5 of the job is getting done.
Therefore 1/9 + 1/x = 1/5
subtracting 1/9 both sides we have
1/9 + 1/x - 1/9= 1/5 - 1/9
1/x = 9/45 - 5/45
1/x = 4/45
x = 45/4 or 11 1/4
The second person takes 11 1/4 hour to finish the working alone.

Directions: Solve the following word problems and show your work. Also write at least 5 word problems of your own.
Q 1: If Tom and his mom takes 6 hours to cleanup Tom's room if they work together. If it takes Tom 10 hours to cleanup his room alone, how many hours does it take his mom to clean up his room?
17
15
20

Q 2: Working together, Larry and Harry take 6 2/3 hours to fix the roof of a house. If Larry takes 15 hours to complete the job alone, how many hours does it take Harry to do the job alone?
12
10
13

Q 3: Jack and Jill can refinish the hardwood floor in a room in 9 hours. If it takes Jill 21 hours to do the job by herself, how many hours does it take Jack to do the hardwood floor by himself?
15 3/4
12 1/8
10 1/3

Q 4: Harry and Jim takes 18 hours to complete installing a deck. If Harry takes 30 hours to do the job alone, how many hours does it take for Jim to do the job alone?
50
45
35

Question 5: This question is available to subscribers only!

Question 6: This question is available to subscribers only!


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