MM207-06 Unit 6 Project_A+

Total points are 40. Points are included with each problem.

Included with each section or problem are reference examples and end of section exercises that can be used as a guide. Be sure to show your work in case partial credit is awarded. To receive full credit, work must be shown if applicable.

 

Section 6.1: Confidence Intervals for the Mean (Large Samples)

 

Find the critical value zc necessary to form a confidence interval at the given level of confidence. (References: definition for level of confidence  page 311, end of section exercises  5 – 8 page 317) (2.5 points each)
 

a.    90%      

½ (1-.90) = 0.05 = 1.645

 

b.    80%

½ (1-.80) = 0.10 = 1.28

 

The new Twinkle bulb has a standard deviation  hours. A random sample of 50 light bulbs is selected from inventory. The sample mean was found to be 550 hours.
 

a.    Find the margin of error E for a 90% confidence interval. (5 points)

     Round your answer to the nearest hundredths. . (References: 

    definition of margin of error on page 312 and example 2 on

    page 312).

 
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