60% of all students at a college still need to take another math class. If 49 students are randomly selected, find the probability that
a. Exactly 26 of them need to take another math class.____
b. At most 31 of them need to take another math class.____
c. At least 28 of them need to take another math class.____
d. Between 25 and 31 (including 25 and 31) of them need to take another math class.____