A bagel shop owner conducts a survey to find out if customers prefer a toasted or untoasted bagel. For one week, they randomly survey $20$ customers who come in for breakfast, $20$ customers who come in for lunch, and $20$ customers who come in for dinner. The results show that $80\%$ of the customers surveyed prefer a toasted bagel. The bagel shop owner concludes that about $80\%$ of all customers prefer a toasted bagel.

Question

A bagel shop owner conducts a survey to find out if customers prefer a toasted or untoasted bagel. For one week, they randomly survey  $20$  customers who come in for breakfast, $20$  customers who come in for lunch, and  $20$  customers who come in for dinner. The results show that  $80\%$  of the customers surveyed prefer a toasted bagel. The bagel shop owner concludes that about  $80\%$  of all customers prefer a toasted bagel.

Which statement best describes the bagel shop owner's conclusion?

Responses

A	The conclusion is valid because the sample is representative of the population.The conclusion is valid because the sample is representative of the population.

B	The conclusion is valid because the survey results showed a percentage higher than  $50\%$  for customers who prefer a toasted bagel.The conclusion is valid because the survey results showed a percentage higher than 50 percent for customers who prefer a toasted bagel.

C	The conclusion is not valid because they did not survey every customer for one week.The conclusion is not valid because they did not survey every customer for one week.

D	The conclusion is not valid because the sample includes customers from different days of the week.The conclusion is not valid because the sample includes customers from different days of the week.

GPT 3.5 · Answer

C The conclusion is not valid because they did not survey every customer for one week.