Answer :
The best point estimate of the mean is 29 pounds.
Sample size n =65; sample means (X) =29; population std (s) =4.3
Since the sample size is more than 30 we can use the central limit theorem. Hence population means estimate is equal to the sample mean which is 29.
At 90% confidence z value = 1.645
Lower limit = X -z * s/[tex]n^{0.5}[/tex]= 29 -1.645 * 4.3/[tex]65^{0.5}[/tex] = 28.1
Upper limit = X -z * s/[tex]n^{0.5}[/tex] = 29 +1.645 * 4.3/[tex]65^{0.5}[/tex] = 29.9
At 95% confidence z = 1.96
Lower limit = X -z * s/[tex]n^{0.5}[/tex] = 29 -1.96 * 4.3/[tex]65^{0.5}[/tex] = 27.9
Upper limit = X -z * s/[tex]n^{0.5}[/tex] = 29 +1.96 * 4.3/[tex]65^{0.5}[/tex]= 30.1
95% confidence interval is larger. It has a wider range of values than 90% confidence. This is because we are covering more area on a normal curve with a higher confidence interval. So mean value is more likely to fall in the 95% range than the 90% range.
To learn more about sample size, mean, median and mode,
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