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7-8 Work Problems

7-8 Work Problems. Objective: To solve work problems. 7-8 Work Problems. Use the formula: Work Rate X time = work done r t = w Work rate means the fractional part of a job done in a given unit of time. 7-8 Work Problems. Example 1:

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7-8 Work Problems

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  1. 7-8 Work Problems Objective: To solve work problems

  2. 7-8 Work Problems • Use the formula: • Work Rate X time = work done • r t = w • Work rate means the fractional part of a job done in a given unit of time.

  3. 7-8 Work Problems • Example 1: • Sheri can rake the lawn in 2 h. Her work rate is the part of the job she can do in 1 h. • r t = w r = w/t r = 1/2 • Therefore  her work is ½ job per hour.

  4. 7-8 Work Problems • Example 2: • Josh can split a cord of wood in 4 days. • His father can split a cord in 2 days. • How long will it take to split a cord of wood if they work together.

  5. 7-8 Work Problems • Example 2: • Josh can split a cord of wood in 4 days. • His father can split a cord in 2 days. • How long will it take to split a cord of wood if they work together. • Step 1: Find the number of days the job will take them. • Step 2: Let x = number of days needed • Step 3: Since josh does the job in 4 days: his work rate = ¼.

  6. 7-8 Work Problems • Example 2: • Josh can split a cord of wood in 4 days. • His father can split a cord in 2 days. • How long will it take to split a cord of wood if they work together. • Step 3: Since his father does the job in 2 days his work rate =1/2.

  7. 7-8 Work Problems • Example 2: • Step 3: Josh’s part + Father’s Job is whole job. • Step 4: Solve 

  8. 7-8 Work Problems • Example 3: Robot A takes 6 min to weld a fender. Robot B takes only 5 ½ min. If they work together for 2 min. How long will it take Robot B to finish welding the fender by itself. • X = number of minutes needed for Robot B to finish. • Robot B’s work rate = 1  5 1/2 • 

  9. 7-8 Work Problems • Example 3: •  • A’s part of job + B’s part = whole job

  10. 7-8 Work Problems • Homework: P. 328 1 – 15 odds

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