Crop researchers plant 15 plots with a new variety of corn. The yields in bushels per acre are: 138.0 139.1 113.0 132.5 140.7 109.7 118.9 134.8 109.6 127.3 115.6 130.4 130.2 111.7 105.5 Assume that Math Notation bushels per acre.
a) Find the 90% confidence interval for the mean yield for this variety of corn.
b) Find the 95% confidence interval.
c) Find the 99% confidence interval.
d) How do the margins of error in (a), (b), and (c) change as the confidence level increases?