Question

A grocery store chain has been tracking data on the number of shoppers that use coupons. The data shows that 71% of all shoppers usecoupons. 36 times out of 40 these results were considered accurate to within 2.5%.What is the confidence interval?16 to 2015.5 to 20.56975 to.7225685 to 735

Answer 1

Answer: (0.685, 0.735)

Explanation:

First, we will compute the confidence level of the given:

$\text{ Confidence Level }=\frac{36}{40}\times100\%=90\%$

They gave us a margin of error of 0.025. From the given, we know that p=71%=0.71.

The confidence interval would then be:

$\begin{gathered} (p-E,p+E) \\ =(0.71-0.025,0.71+0.025) \\ =(0.685,0.735) \end{gathered}$

Therefore, the confidence interval would then be (0.685, 0.735)