In a study of the accuracy of fast food drive-through orders, Restaurant A had 2

Question

In a study of the accuracy of fast food drive-through orders, Restaurant A had 299 accurate orders and 67 that were not accurate. a. Construct a 90 % confidence interval estimate of the percentage of orders that are not accurate. b. Compare the results from part (a) to this 90 % confidence interval for the percentage of orders that are not accurate at Restaurant B: 0.172 less thanpless than0.237. What do you conclude? Since the two confidence intervals overlap, neither restaurant appears to have a significantly different percentage of orders that are not accurate. B. No conclusion can be made because not enough information is given about the confidence interval for Restaurant B. C. Since the upper confidence limit of the interval for Restaurant B is higher than both the lower and upper confidence limits of the interval for Restaurant A, this indicates that Restaurant B has a significantly higher percentage of orders that are not accurate. D. The lower confidence limit of the interval for Restaurant B is higher than the lower confidence limit of the interval for Restaurant A and the upper confidence limit of the interval for Restaurant B is also higher than the upper confidence limit of the interval for Restaurant A. Therefore, Restaurant B has a significantly higher percentage of orders that are not accurate.

Explanation / Answer

for restaurant A:

sample proportion phat =x/n=67/299=0.224

std error =(phat*(1-pha)/n)1/2 =0.0241

for 90% CI ; critical value of z =1.6449

therefore 90% confidence interval estimate of the percentage of orders that are not accurate for restaurant A

=sample proportion -/+ z*std error =0.1844 to 0.2637

. Since the two confidence intervals overlap, neither restaurant appears to have a significantly different percentage of orders that are not accurate.

please revert for any clarification required,

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