Calculate the lower and upper limits of the 90% confidence interval for a sample of N = 29 with a mean = 137.98 and standard error of the mean = 4.98.
A) (129.51, 146.45)
B) (124.22, 151.74)
C) (131.30, 144.66)
D) (127.78, 148.18)

Question

Calculate the lower and upper limits of the 90% confidence interval for a sample of N = 29 with a mean  = 137.98 and standard error of the mean  = 4.98.
A) (129.51, 146.45) 
B) (124.22, 151.74) 
C) (131.30, 144.66) 
D) (127.78, 148.18)

Quizplus · Accepted Answer

To calculate the lower and upper limits of the 90% confidence interval, we use the formula:
CI = X̄ ± (Zα/2 x SE)
Where X̄ is the sample mean, SE is the standard error of the mean, and Zα/2 is the critical value of the standard normal distribution for the given confidence level (90% in this case).
Substituting the given values, we get:
CI = 137.98 ± (1.645 x 4.98)
Calculating the values, we get:
CI = (129.51, 146.45)
Therefore, the best choice is A.

Calculate the Lower and Upper Limits of the 90% Confidence