QUESTION 19 If the point estimate is 50 and the margin of error is 4. What is the confidence interval? O A. 12.5 to 24.5 O B. 46 to 54 O C. 44 to 55 O D. 49.6 to 50.4 QUESTION 20 If the sample size is 25. What is t for a 95% confidence interval? O A. 2.060 O B. 2.492 O C. 2.064 O D. 1.71 QUESTION 21 A random sample of 40 students has a test score with mean equal to 81.5 and standard deviation to 10.2. What is the 90% confidence interval for the mean score of the population? O A. 51.8 to 92.3 O B. 78.8 to 84.2 O C. 66.3 to 89.1 O D. 71.8 to 93.5QUESTION 17 Midterm grades of students in statistics class are approximately normal with a mean of 82 and a standard deviation of 4. Which choice correctly describes how to find the proportion of students that have a midterm grade lower than 86? O A. Find the area to the left of z = 1 under a standard normal curve. O B. Find the area between z = -1 and z = 1 under a standard normal curve. O C. Find the area to the right of z = 1 under a standard normal curve. O D. Find the area to the right of z = -1 under a standard normal curve. QUESTION 18 What would happen to the confidence interval if you calculated a 99% confidence interval rather than a 95% confidence interval? O A. It will be narrower O B. It will not change O C. The sample size will increase O D. It will become widerQUESTION 25 Average IQ score of a sample of 64 students selected from a public high school is 85 with a standard deviation of 8. What is the 99% confidence interval for the mean IQ score of all students at this school? O A. 80.91 to 90.02 B. 82. 42 to 87.58 O C. 83.45 to 87.58 O D. 83.23 to 88.27 QUESTION 26 If a sample of n = 50 is taken from a population whose standard deviation is equal to 10, what is the standard error of the mean? O A. 1.4142 O B. 10.6543 O C. 15.8114 O D. 2.4293 QUESTION 27 Scores on a Statistics test follow a normal distribution with a mean of 82 and a standard deviation of 3.5. What percentage of students have scores 90 or higher? O A. 0.0110 O B. 2.2831 O C. 0.9890 O D. 0.4890QUESTION 33 A bag contains 2 red, 3 green and 2 blue balls. Two balls are drawn at random without replacement. What is probability that both balls drawn are red? O A. 2/49 O B. 1/21 O C. 1/7 O D. 2/7QUESTION 22 A sample of 100 observations produced a mean of 53 and a standard deviation of 5. What is the 95% confidence interval for the population mean? O A. 52.02 to 53.98 O B. 52. 18 to 53.82 O C. 51.71 to 54.29 O D. 53. 11 to 54.26 QUESTION 23 What is the area under the standard normal curve in between 0 and 2.85? O A. 0.0022 O B. 0.4978 O C. 0.6103 O D. 0.9978 QUESTION 24 What is the area under the standard normal curve to the left of 2.85? O A. 0.0022 O B. 0.4978 O C. 0.6103 O D. 0.9978QUESTION 30 From a population that is normally distributed, a sample of 25 is selected and the standard deviation of the sample is computed. For the interval estimation of i, what kind of distribution should be used? O A. t distribution with 25 degrees of freedom O B. t distribution with 24 degrees of freedom O C. normal distribution with z = 1.96 O D. normal distribution with z = 1.645 QUESTION 31 A random sample of 100 observations is to be drawn from a population with a mean of 40 and a standard deviation of 15. What is the probability that mean of the sample is less than 45? O A. 0.4536 O B. 0.9010 O C. 0.9996 O D. 0.9999 QUESTION 32 Find the probability for a student scoring less than 75 out of 100, with a mean of 73 and a standard deviation of 5. O A. 0.6554 O B. 0.7234 O C. 0.7967 O D. 0.8235QUESTION 28 Scores on a Statistics test follow a normal distribution with a mean of 82 and a standard deviation of 3.5. What percentage of students have scores less than 75? O A. 0.4772 O B. 0.9772 O C. 0.0228 O D. 0.0201 QUESTION 29 In developing an interval estimate, if the population standard deviation is unknown, which of the following is true? O A. It is impossible to construct an interval estimate. O B. The sample standard deviation can be used. O C. It is assumed that the population standard deviation is 0. O D. It is assumed that the population standard deviation is 1