An optometry practitioner group has found that half of those who need vision correction are patients who require bifocal lenses.
a. For a randomly selected group of three people who require vision correction, what is the probability that all three will require bifocals? What is the probability that none of the three will require bifocals?
b. If the three individuals had all been selected from an organization consisting of retirees over age 65, do you believe the joint probabilities calculated in part (a) would still be accurate? If not, why not?