Use the following to answer question 12. An agricultural researcher plants 100 plots with a new variety of corn. The average yield for these plots is X - 1 bushels per acre. Assume that the yield per acre for the new variety of com follows a normal distribution with unknown mean / and standard deviation O - 20 bushels per acre. 12. A 90% confidence interval for LL is a. 150 2.00. b. 150 3.29. C. 150 3.92. d. 150 32.90. Use the following to answer question 13. You measure the weights of a random sample of 25 male runners. The same mean is X = 60 kilograms (kg). 13 Suppose that the mean weights of male runners follow a normal distribution with unknown mean / and standard deviation O = > kg. A 95% confidence internal for / is 59.61 to 60.39. 59 to 61. 58.04 to 61.96. 50.2 to 69.8. Use the following to answer questions 14-15. The heights of 15-year-old American boys, in inches, are normally distributed with mean / and standard deviation O = 2. 4. I select a simple random sample of four 15-year-old American boys and measure their heights. The four heights, in inches, are 63 69 62 66 14. Based on these data, a 99% confidence interval for / , in inches, is a. 65.00 1.55. b . 65.00 + 2.35. C. 65.00 + 3.09. d. 65.00 + 4.07. 15. If I wanted the margin of error for the 99% confidence interval to be + 1 inch, I should select a simple random sample of size NN 16. 39 Focus Lo TE