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Inference from sample statistics and margin of error SAT question
Math · Problem-Solving and Data Analysis · Medium · Answer it here, explanation included.
A store manager reviewed the receipts from 80 customers who were selected at random from all the customers who made purchases last Thursday. Of those selected, 20 receipts showed that the customer had purchased fruit. If 1,500 customers made purchases last Thursday, which of the following is the most appropriate conclusion?
ExplanationShow
Choice D is correct. It’s given that the manager took a random selection of the receipts of 80 customers from a total of 1,500. It’s also given that of those 80 receipts, 20 showed that the customer had purchased fruit. This means that an appropriate estimate of the fraction of customers who purchased fruit is 
, or 
. Multiplying this fraction by the total number of customers yields 
. Therefore, the best estimate for the number of customers who purchased fruit is 375.
Choices A and B are incorrect because an exact number of customers can’t be known from taking a random selection. Additionally, choice A may also be the result of a calculation error. Choice C is incorrect and may result from a calculation error.
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