In: Statistics and Probability
A. How many samples do you need to create a 99% confidence interval for u with a margin of error fo 10 and standard deviation of 28?
B. Five a 95% percent confidence interval for the true mean if the sample mean is 86.5, the sample size is 70, and the standard deviation is 12.2.
Solution :
Given that,
=86.5
= 12.2
n = 70
At 95% confidence level the z is ,
= 1 - 95% = 1 - 0.95 = 0.05
/ 2 = 0.05 / 2 = 0.025
Z/2 = Z0.025 = 1.96
Margin of error = E = Z/2* ( /n)
= 1.96 * (12.2 / 70)
= 2.8580
At 95% confidence interval estimate of the population mean is,
- E < < + E
86.5 - 2.8580 < < 86.5 +2.8580
83.6420< < 89.3580
(83.6420 , 89.3580 )