In a survey of nursing students pursuing a master's degree, 75 percent stated that they expect to be promoted to a higher position within one month after receiving the degree. If this percentage holds for the entire population, find, for a sample of 15 students, the probability that the
number expecting a promotion within a month after receiving their degree is
a) six;
b) at least seven;
c) no more than five;
d) between six and nine, inclusive.