Question

gleater than 700 pounds? DIe 81 31 female giraffes are chosen. The mean height is found to be 15 feet. Assume that the population standard deviation for the height of female giraffes is。 5 feet. Calculate the 85% confidence interval of for population mean height of female giraffes. 16) A sample of 21 male giraffes are chosen. The mean height is found to be 17.5 feet. The standard deviation of the sample is found to be 7 feet Calculate the 80% confidence interval of for population mean height of male giraffes. (17) Homeowners claim that the mean speed of automobiles traveling on their street is greater than 35 mph. A random sample of 100 automobiles has a mean speed of 36 mph. Assume the population standard deviation is 4 mph. Since your friend lives on this street, you decide to test this claim to see if it is true. (i) State the null and alternative hypotheses. (ii) Calculate the P-value for this test. (iii) Is there enough evidence to support this claim. at α :0.05? (18) Employees at a construction and mining company claim that the mean salary of the company's mechanical engineers is less than that of one of its competitors, which is $68,000. A random sample of 20 of the company's mechanical engineers has a mean salary of $66,900. standard deviation is $5,500 and the population is normally distributed. You suspect employees claim might be true and decide to test it. (i) State the null and alternative hypotheses (ii) Calculate the P-value for this test. (iii) Is there enough evidence to support this claim at α-0.05? Assume the population that the

17 and 18 please. Thank you.

Answer 1

17) Answer - Null Hypothesis H0 : μ Date: ----20/5/2019 35 Alternative Hypothesis H1 : μ > 35 Under HO, the test statistics is z-i-μ a/Vn 36-35 2.5 0.4 4/V100 i) At 5% level of significance , the critical value of Z is 1.96 The P-Value is 0.00621 i) Decision: Since Z calculated is greater than tabulated Z we reject null hypothesis, and conclude that the mean speed of automobiles traveling on their street is greater than the speed limit of 35 miles per hour

18) Answer: Claim: The mean salary of the company's mechanical engineers is less than that of one of its competitons, which is S68,000. Date: ----20/5/2019 Sample size n 20 Sample mean = 66900 Population standard deviation σ-5500 Null and alternative hypothesis is H0 : μ > 68000 H1 : μ < 68000 Test statistic is 66900 68000 -1100 500/V20-1229.837 =-0.89 Critical value = 1.64 Z<critical value we fail to reject null hypothesis. Conclusion: There is sufficient evidence to support employees claim. That is the mean salary of the company's mechanical engineers is less than that of one of its competitons which is S68,000.