SOLUTION: 1. You measure 33 backpacks' weights, and find they have a mean weight of 44 ounces. Assume the population standard deviation is 12.1 ounces. Based on this, what is the maximal mar

Question 1175140: 1. You measure 33 backpacks' weights, and find they have a mean weight of 44 ounces. Assume the population standard deviation is 12.1 ounces. Based on this, what is the maximal margin of error associated with a 90% confidence interval for the true population mean backpack weight.Give your answer as a decimal, to two places.
2. You intend to estimate a population mean μ with the following sample.
80.4
78.8
68.6
52.4
59.4
63.8
61.2
67.4
63
72.1
53.5
77.8

You believe the population is normally distributed. Find the 80% confidence interval. Enter your answer as an open-interval (i.e., parentheses) accurate to twp decimal places (because the sample data are reported accurate to one decimal place).
80% C.I. =
Answer should be obtained without any preliminary rounding. However, the critical value may be rounded to 3 decimal places.
Answer by ewatrrr(24785) (Show Source): You can put this solution on YOUR website!


Hi
1) Normal Distribution: the population standard deviation σ  = 12.1 ounces 
   Sample Size is 33: Sample mean = 44  
90% confidence Interval, find ME 
   ME = 1.645 (12.1)/√33 = 3.465
CI = 44 ± 3.465

2)  Normal Distribution:  Sample of 12    mean = 66.533   sd = 9.012  
80% CI  z = 1.362 df 11
ME == = 3.543
80% C.I. = (62.99,70.08)

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

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