An aerospace engineering student performs an experiment in a wind tunnel to determine the lift coefficient of an airfoil. The student takes 31 measurements of the vertical force using a force balance, yielding a sample mean value of 43.80 N and a sample variance of 8.87 N^2. Determine (a) the percent probability that an additional measurement will be between 45.56 N and 48.20 N, (b) the range (in N) over which the true mean value will be, assuming 90 % confidence, and (c) the range (in N^2) over which the true variance will be assuming 90 % confidence.