Question

A survey of 25 grocery stores revealed that the mean price of a gallon of milk was $2.98, with a standard error of $0.10. What is the 95% confidence interval to estimate the true cost of a gallon of milk?

Answer 1

Answer:

95% confidence interval: (2.784,3.176)

Step-by-step explanation:

We are given the following information in the question:

Sample size, n = 25

Sample mean = $2.98

Standard error = $0.10

Alpha = 0.05

95% confidence interval:

$\mu \pm z_{critical}(\text{Standard error})$

Putting the values, we get,

$z_{critical}\text{ at}~\alpha_{0.05} = 1.96$

$2.98 \pm 1.96(0.10) = 2.98 \pm 0.196 = (2.784,3.176)$