(4) Imagine that we take a sample from a population of interest. Sample data For the following questions use the sample values to the right: 21 20 18 15 Assume that this sample accurately reflects the mean and standard 16 18 deviation of the population so you can use the normal distribution and 19 18 Z scores for the problems below. (If you've read ahead in your book or lab manual you know we should really use t scores, don't worry about this right now, use the Z scores) (a) Assuming that the population data is normally distributed, what is the value that you expect 67% of the data in the population to be smaller than? (round to nearest 0.01) (b) What is your best estimate for the IOR of the population data? (round to nearest 0.01)