Twenty-one independent measurements were taken of the hardness (on the Rockwell C scale) of HSLA-100 steel base metal, and another 21 independent measurements were made of the hardness of a weld produced on this base metal. The standard deviation of the measurements made on the base metal was 3.06, and the standard deviation of the measurements made on the weld was 1.41. Assume that the measurements are independent random samples from normal populations. Can you conclude that measurements made on the base metal are more variable than measurements made on the weld?

A coin-operated drink machine was designed to discharge a mean of 8 fluid ounces of coffee per cup. In a test of the machine, the discharge amounts in 22 randomly chosen cups of coffee from the machine were recorded. The sample mean and sample standard deviation were 8.11 fluid ounces and 0.19 fluid ounces, respectively. If we assume that the discharge amounts are approximately normally distributed, is there enough evidence, to conclude that the population mean discharge, μ, differs from 8 fluid ounces? Use the 0.05 level of significance. Perform a two-tailed test. Then complete the parts below. Carry your intermediate computations to three or more decimal places. (If necessary, consult a list of formulas.) (a) State the null hypothesis H and the alternative hypothesis H₁. : (b) Determine the type of test statistic to use. (Choose one) (c) Find the value of the test statistic. (Round to three or more decimal places.) 0 (d) Find the p-value. (Round to three or more decimal places.) (e)…

A simple random sample of pulse rates of 25 women from a normally distributed population results in a standard deviation of 12.3 beats per minute. The normal range of pulse rates of adults is typically given as 60 to 100 beats per minute. If the range rule of thumb is applied to that normal​ range, the result is a standard deviation of 10 beats per minute. Use the sample results with a 0.10 significance level to test the claim that pulse rates of women have a standard deviation equal to 10 beats per minute. Complete parts​ (a) through​ (d) below. a. Identify the null and alternative hypotheses. Choose the correct answer below.     A. H0: σ=10 beats per minute H1: σ≠10 beats per minute   B. H0: σ=10 beats per minute H1: σ<10 beats per minute   C. H0: σ≥10 beats per minute H1: σ<10 beats per minute   D. H0: σ≠10 beats per minute H1: σ=10 beats per minute b. Compute the test statistic.   χ2=nothing ​(Round to three decimal places as​ needed.) c.…

A simple random sample of 37 men from a normally distributed population results in a standard deviation of 11.4 beats per minute. The normal range of pulse rates of adults is typically given as 60 to 100 beats per minute. If the range rule of thumb is applied to that normal range, the result is a standard deviation of 10 beats per minute. Use the sample results with a 0.10 significance level to test the claim that pulse rates of men have a standard deviation equal to 10 beats per minute. Complete parts (a) through (d) below. a. Identify the null and alternative hypotheses. Choose the correct answer below. O A. Ho: 0= 10 beats per minute O B. Ho: 0± 10 beats per minute H,: 0+ 10 beats per minute H,: 0= 10 beats per minute O C. Ho: o2 10 beats per minute H1: o< 10 beats per minute O D. Ho: 0 = 10 beats per minute H: o<10 beats per minute