Suppose an ad for an automotive service centre claims that at least 90% of its customers would gladly recommend the centre to friends. Since you have heard nothing but complaints about this service centre, you doubt that the claim is true. Your friend who works at the service centre helps you to conduct a survey of 300 customers, and you discover that only 87% of them would recommend the centre to friends. Assume that if the centre's claim were true, sample proportions would be normally distributed with a mean of 0.90 and a standard deviation of 0.01732.Does your sample result indicate that the centre's ad overstates the percentage of customers who would provide a positive recommendation?

  • CreatedJuly 12, 2015
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