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 95% confidence interval to estimate the true cost of a 4-litre bag of milk?
A) $2.81 to $3.15
B) $2.94 to $3.02
C) $2.78 to $3.18
D) $2.95 to $3.01
E) $2.73 to $3.23

Question

Quizplus · Accepted Answer

The 95% confidence interval is calculated as the sample mean ± (Z-score * standard error). For a 95% confidence level, the Z-score is approximately 1.96. Thus, the interval is $2.98 ± (1.96 * $0.10), which is $2.78 to $3.18.

A Survey of 25 Grocery Stores Revealed That the Average