Police recorded the average speed of cars driving on a busy street by a school. For a sample of 16 speeds, it was determined that the average amount over the speed limit for the 16 speeds was 13.3 mph with a standard deviation of 6 mph. The 90% confidence interval estimate for this sample is 10.67 mph to 15.93 mph. a) What is the margin of error for this problem? b) What size sample is needed to reduce the margin of error to no more than ±1? a) The margin of error is nothing mph. b) The sample size should be at least nothing speeds.
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Inference for Quantitative Data: Means
Quiz 27
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