The ages of Americans who died from alcohol poisoning are normally distributed with mean 46.6 years and standard deviation 12.5 years (Source: Centers for Disease Control and Prevention).
a. Find the proportion of alcohol-poisoning fatalities in which the victims were under the minimum drinking age (21 years).
b. Find the proportion of alcohol-poisoning fatalities in which the victims were between 50 and 60 years of age.
c. Find the proportion of alcohol-poisoning fatalities in which the victims were senior citizens (at least 65 years of age).