Question

1. A machine produces 5-inch nails. A sample of 12 nails was selected and their lengths determined. The results are as follows: 4.91 4.97 4.80 4.81 4.93 4.82 4.84 4.81 4.97 4.95 4.82 4.86 Assuming that a = 0.05, test the hypothesis that the population mean is equal to 5. · State the null and alternate hypotheses · Calculate the mean and standard deviation · Determine which test statistic applies, and calculate it · Determine the critical value(s). · State your decision: Should the null hypothesis be rejected? 2. A sample of size n = 20 is selected from a normal population to construct a 95% confidence interval estimate for a population mean. The interval was computed to be (1.60 to 6.50). Determine the sample standard deviation.