The mean age when smokers first start in the past has been 13 years old with a population standard deviation of 2 years. A researcher thinks that smoking age has significantly changed. A survey of smokers of this generation was done to see if the mean age is no longer 13 years old. The sample of 31 smokers found that their mean starting age was 12.5 years old. Use the Classical Method (compare the test statistic with the Z-critical value) to determine if there is sufficient evidence to support the repearcher's claim at a 10% significance level? Ho: μ=13 years H: #13 years Remember that since this is a two-tailed test, we compare the absolute value of the the test statistic with the absolute value of the Z-critical value. (absolute value makes a number positive) a. Determine the test statistic. Round to 3 decimals. z= b. Find the critical value for z. Round to 3 decimals. Z-crit c. Make a decision. O Reject the null hypothesis since the absolute value of the z-score for the data is greater than the absolute value of the Z-critical value. O Fail to reject the null hypothesis since the absolute value of the z-score for the data is NOT greater than the absolute value of the Z-critical value. d. Write the conclusion. There is sufficient evidence to support the claim that the mean age when smokers first start smoking is no longer 13 years old. There is not sufficient evidence to support the claim that the mean age when smokers first start smoking is no longer 13 years old. Question Help: Video Submit Question