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  1. M

    Construct the margin of error and confidence interval

    A market research firm supplies manufacturers with estimates of the retail sales of their products from samples of retail stores. Marketing managers are prone to look at the estimate and ignore sampling error. An SRS of 17 stores this year shows mean sales of 85 units of a small appliance, with...
  2. M

    How to find the confidence interval

    Randomly selected 25 student cars have ages with a mean of 7.4 years and a standard deviation of 3.4 years, while randomly selected 15 faculty cars have ages with a mean of 5.2 years and a standard deviation of 3.3 years. Construct a 99% confidence interval estimate of the difference μs−μf...