Question

Test No. 3 ( (Form B)Math 100 Spring 2019 I. Multiple-choice (Circle the letter of your answer): Questions No. 1 through No. 5 refer to the following: A continuous s has a normal distribution with the mean of 80 and standard deviation of 15 random variable x (1) The mode of the variable s is A 80 (B) 15 (C) 40 (D) Unknown (2) The z-score for the mode of x : (A) I (3) The p (B) 0.S ity that the -value is greater than equal 80 is 0 (D) Unknown (A)I (B 0.50 (C)0 (D) Unknowrn (4) A random sample of 25 values of z is randomly choeen from the population. Then the mean and standard deviation for the sampling distribution of the sample mean t is (5) A random sample of 25 values of z is randomly chosen from the population. Then the z- is so from the sampling distribution of the sample mean score for the sample mean (A)1 (B) 0.5 (C)O (D) Unknown (6) Suppose that 3% of the people in a group of adults have attempted suicide. Suppose a sample of 200 adults is selected at random from this group. The mean and the standard deviation of the sampling distribution for the sample proportion of the adults who have attempted suicide are (approximately): (B) μ,-0.97 and σ.. 003 resp. (D) P.-00012 and ơp-0.03 resp. μ,-0.03 and σ#-0.97 resp. ey14-0.03 and σβ 0012 resp. Use the following information to answer questions 7-9: A sample of 40 cars traveling on Interstate Highway 1-78 produced a mean of 50 miles per hour and a standard deviation of 10 miles per hour (7) The point estimate for the mean, in mph, of the underlying population is: (D) 39 (A) 50 (B) 40 (C) 49 (8) To construct a 95% confidence interval for the mean speed of the underlying population, the degrees of freedom for the standard sample statistichis situation -: (A) 50 (B) 40 (C) 49 (D) 39 (9) Which of the following is the correct critical value of t for 95% confidence interval for the popu- lation mean μ? (A) to oas 2.009 for df = 49 (B) to os 1.676 for df-49 (C) to 025 -2.023 for 39 (D) fo.os 1.685 for df-39 (10) Which of the following describes a correct effect on which the width of a confidence interval? I. As sample size increases, the width of the confidence interval increases. II. As the confidence level increases, the width of the confidence interval increases. III. As the standard error of the estimates increases, the width of the confidence interval decreases (A) I only (B) II only (C) I and II DL, II, and III

Answer 1

Uptill ques 6, the answers are correct.

So, I presumably answer from ques 7

7) A) part is correct

8) D) part is correct. Since the degrees of freedom for a t statistic is n-1. Here, n=40

9) C) part is correct. The test should be two tailed hence we look for t(0.025, 39)

10) B) part is correct. Only the second statement is true