Suppose that the return for a particular investment is normally distributed with a population mean of 11.1% and a population standard deviation of 5.4%. a. What is the probability that the investment has a return of at least 20%? (2 marks) b. What is the probability that the investment has a return of 10% or less? (2 marks). A person must score in the upper 1% of the population on an IQ test to qualify for membership with Mensa, the international high IQ society. If IQ scores are normally distributed with a mean of 100 and a standard deviation of 15, what score must a person have to qualify for Mensa?