A survey of 25 grocery stores revealed that the average price of a 4-litre bag of milk was $2.98 with a standard error of $0.10. What is the 98% confidence interval to estimate the true cost of a 4-litre bag of milk?
A) $2.73 to $3.23
B) $2.85 to $3.11
C) $2.94 to $3.02
D) $2.95 to $3.01
E) $2.77 to $3.19

Question

Quizplus · Accepted Answer

The 98% confidence interval is calculated as:mean +/- 2.326 * standard error= 2.98 +/- 2.326 * 0.10= 2.98 +/- 0.2326= (2.7474, 3.2126)Therefore, the 98% confidence interval is $2.75 to $3.21, which is closest to choice A.

A Survey of 25 Grocery Stores Revealed That the Average