6.30 Quartiles and outliers For an approximately normally distributed random variable X with a mean of 200 and a standard deviation of 36,

a. Find the z-score corresponding to the lower quartile and upper quartile of the standard normal distribution.

b. Find and interpret the lower quartile and upper quartile of X.

c. Find the interquartile range (IQR) of X.

d. An observation is a potential outlier if it is more than 1.5 * IQR below Q1 or above Q3. Find the values of X that would be considered potential outliers.