A sample of 200 smokers were asked at what age they started smoking. The mean age was 18.3 years. The population standard deviation is 4.35 years. Construct a 90% confidence interval for the mean age that all smokers begin smoking. Fill in the blanks with the appropriate responses. Round numbers to three decimal places. We are 90% confident that the age at which smokers begin smoking is between and years.
Added by Brian R.
Step 1
For a 90% confidence interval, the critical value (z-score) is 1.645. This value is obtained from the standard normal distribution table, where 90% of the area under the curve is between -1.645 and 1.645. Show more…
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