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Qnt275r6 Wk4 Practice Set

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Practice Set 4
QNT/275 Version 6
1
Copyright © 2017 by University of Phoenix. All rights reserved.
University of Phoenix Material
Practice Set 4
Practice Set 4
1. Find z for each of the following confidence levels. Round to two decimal places.
A. 90%
NORMSINV(

= 
B. 95%
NORMSINV(

= 
C. 96%
NORMSINV(

= 
D. 97%
NORMSINV(

= 
E. 98%
NORMSINV(

= 
F. 99%
NORMSINV(

= 
2. For a data set obtained from a random sample, n = 81 and x = 48.25. It is known
that σ = 4.8.
A. What is the point estimate of μ? Round to two decimal places
n = 81
x = 48.25
σ = 4.8
The point estimate μ is 48.25.

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Practice Set 4
QNT/275 Version 6
2
Copyright © 2017 by University of Phoenix. All rights reserved.
B. Make a 95% confidence interval for μ. What is the lower limit? Round to two decimal
places.
 
  

C. Make a 95% confidence interval for μ. What is the upper limit? Round to two decimal
places.
 
  

D. What is the margin of error of estimate for part b? Round to two decimal places.




3. Determine the sample size (nfor the estimate of μ for the following.
A. E = 2.3, σ = 15.40, confidence level = 99%. Round to the nearest whole number.





 



B. E = 4.1, σ = 23.45, confidence level = 95%. Round to the nearest whole number.






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Practice Set 4 QNT/275 Version 6 University of Phoenix Material Practice Set 4 Practice Set 4 1. Find z for each of the following confidence levels. Round to two decimal places. A. 90% NORMSINV( 1−0.90 ) = ±1.645 2 B. 95% NORMSINV( 1−0.95 ) = ±1.960 2 C. 96% NORMSINV( 1−0.96 ) = ±2.054 2 D. 97% NORMSINV( 1−0.97 ) = ±2.170 2 E. 98% NORMSINV( 1−0.98 ) = ±2.326 2 F. 99% NORMSINV( 1−0.99 2 ) = ±2.576 2. For a data set obtained from a random sample, n = 81 and x = 48.25. It is known that σ = 4.8. A. What is the point estimate of μ? Round to two decimal places n = 81 x = 48.25 σ = 4.8 The point estimate μ is 48.25. Copyright © 2017 by University of Phoenix. All rights reserved. 1 Practice Set 4 QNT/275 Version 6 B. Make a 95% confidence interval for μ. What is the lower limit? Round to two decimal places. 𝑥̅ ± 𝑍𝛼/2 𝜎/√𝑛 48.25 ± 1.96 ∗ 4.8/√81 48.25 ± 1.0453 𝐿𝑜𝑤𝑒𝑟 𝑙𝑖𝑚𝑖𝑡 = 47.20 C. Make a 95% confidence interval for μ. What is the upper limit? Round to two decimal places. 𝑥̅ ± 𝑍𝛼/2 𝜎/√𝑛 48.25 ± 1.96 ∗ 4.8/√81 48.25 ± 1.0453 𝑈𝑝𝑝𝑒𝑟 𝑙𝑖𝑚𝑖𝑡 = 49.30 D. What is the margin of error of estimate for part b? Round to two decimal places. 𝐸 = 𝑍𝛼/2 𝜎/√𝑛 𝐸 = 1.96 ∗ 4.8/√81 𝐸 = 1.05 3. Determine the sample size (nfor the estimate of μ for the following. A. E = 2.3, σ = 15.40, confidence level = 99%. Round to ...
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