Hello, This is my 4th attempt at getting a confidence interval for this problem.
ID: 3384931 • Letter: H
Question
Hello,
This is my 4th attempt at getting a confidence interval for this problem. So I hope the tutor is actually reading this. Please see the table below. I need the unanswered boxes answers, then a Confidence Interval Determined for the sum of two variances?
Mean of Public
27.5
Mean of private
26.5
Standard Deviation of public
606.194
Standard Deviation of private
507.35
Count of public
26
Count of private
26
Difference in mean[RB1]
4.6278
Standard Deviation of public squared
24.62
Standard Deviation of private squared
22.52
Variance (public)/count __________
Variance (private)/count
________________
Sum of standard deviation values
Square root result of previous formula
_________
z value for 95% confidence interval:___________
Margin of error: _________
Upper Limit:_________
Lower Limit:_______
Due to the difference in variances, we find that the confidence interval of 95% for this data is ______?
Mean of Public
27.5
Mean of private
26.5
Standard Deviation of public
606.194
Standard Deviation of private
507.35
Count of public
26
Count of private
26
Difference in mean[RB1]
4.6278
Standard Deviation of public squared
24.62
Standard Deviation of private squared
22.52
Variance (public)/count __________
Variance (private)/count
________________
Sum of standard deviation values
Square root result of previous formula
_________
z value for 95% confidence interval:___________
Margin of error: _________
Upper Limit:_________
Lower Limit:_______
Explanation / Answer
Given SD (public) = 24.62 so Var(public) = 606.194 and SD(private) = 22.52 so Var(private) = 507.35
Variance (public)/count = (606.194) / 26 = 23.3151
Variance (private)/count = 507.35 / 26 = 19.5135
Sum of standard deviation values = 24.62+22.52 = 47.14 (but it is not required for further process) So i calculated
as 23.3151 + 19.5135 = 42.8286
Square root result of previous formula = 6.5444
z value for 95% confidence interval: 1.96
Margin of error: 1.96* 6.5444 = 12.827
Upper Limit: 4.6278 + 12.827 = 17.4548
Lower Limit: 4.6278 - 12.827 = -8.1992
The confidence interval of 95% for the data is (-8.1992, 17.4548)
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