A marketing research company is trying to determine which of two brands of soft drinks college students prefer. A random sample of 79 college students produced the following 99% confidence interval fo:
a) The mean preference of college students for brand A lies between 60% and 70%.
b) The mean preference of college students for brand B lies between 45% and 55%.
c) The proportion of college students who prefer brand A is between 0.6 and 0.7.
d) The proportion of college students who prefer brand B is between 0.45 and 0.55.