A standard normal density is a probability density function for a random variable that is normally distributed with population mean = 0 and population variance = 1. Using a table of standard normal probabilities, such as Table A1 in your textbook, answer the following questions:

a) If a random variable has a standard normal density, what is the probability that this random variable is less than 1.5?

b) If a random variable has a standard normal density, what is the probability that this random variable is less than -2.0?

c) If a random variable has a standard normal density, what is the probability that this random variable is between -2.0 and 1.5?

d) Find the 68% critical value for a random variable that has a standard normal density.