IQ scores are normally distributed with a mean of 100 and a standard deviation of 15. Based on this distribution, determine:
a. The percentage of IQ scores between 100 and 120.
b. The probability of selecting two persons, at random: one with an IO >= 110 and the other with an IQ less than 80.
c. The percentile corresponding to an IQ score of 125.
d. The likelihood of selecting a person, at random, with an IQ less than 75 or an IQ >= 140