An agricultural researcher plants 100 plots with a new variety of corn. The sample average yield for these plots is 150 bushels per acre. Assume that the yield per acre for the new variety of corn follows a normal distribution with unknown population mean and known population standard deviation 20 bushels per acre. Which of the following would produce a confidence interval with a smaller margin of error (narrower interval) than the 90% confidence interval you computed above? Plant 500 plots rather than 100 Compute a 99% confidence interval rather than a 90% confidence interval. The increase in confidence indicates that we have a better interval Plant only 25 plots rather than 100 because 25 are easier to manage and control None of the above