SOLUTION: 4. You want to obtain a sample to estimate a population mean. Based on previous evidence, you believe the population standard deviation is approximately σ=36.7. You would like

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Question 1175015: 4. You want to obtain a sample to estimate a population mean. Based on previous evidence, you believe the population standard deviation is approximately
σ=36.7. You would like to be 90% confident that your esimate is within 0.1 of the true population mean. How large of a sample size is required? n =
Do not round mid-calculation. However, use a critical value accurate to three decimal places — this is important for the system to be able to give hints for incorrect answers
5. In a survey, 12 people were asked how much they spent on their child's last birthday gift. The results were roughly bell-shaped with a mean of $42 and standard deviation of $13. Construct a confidence interval at a 95% confidence level.Give your answers to one decimal place.
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!

Hi

4.  population standard deviation  σ=36.7
 90% confident level
ME =+z%2Asigma%2Fsqrt%28n%29  0r n = (t*sigma/ME)^2
 n = [(1.96(36.7)/(.1)]^2 = 


5.      x̄ = 42    sd = 13     95% confidence level
ME =+t%2Asigma%2Fsqrt%28n%29
ME = 2.201(13)/√12           |df = 11  (n-1)
42 - ME < mu < 42 + ME
Wish You the Best in your Studies.
Confidence Level	80%	90%	95%	98%	99%
Two-sided test p-values	0.2	0.1	0.05	0.02	0.01
One-sided test p-values	0.1	0.05	0.025	0.01	0.005
Degrees of Freedom (df=n-1)					
               1	3.078	6.314	12.71	31.82	63.66
               2	1.886	2.92	4.303	6.965	9.925
               3	1.638	2.353	3.182	4.541	5.841
               4	1.533	2.132	2.776	3.747	4.604
               5	1.476	2.015	2.571	3.365	4.032
               6	1.44	1.943	2.447	3.143	3.707
               7	1.415	1.895	2.365	2.998	3.499
               8	1.397	1.86	2.306	2.896	3.355
               9	1.383	1.833	2.262	2.821	3.25
              10	1.372	1.812	2.228	2.764	3.169
              11	1.362	1.796	2.201	2.718	3.106