Using the combination formula, the probabilities are given as follows:
a) P(4 seniors) = 0.0008.
b) P(1 of each) = 0.0999.
c) P(2 sophomore, 2 freshmen) = 0.0225.
d) P (at least one senior) = 0.5866.
<h3>Combination Formula</h3>
is the number of different combinations of x objects from a set of n elements, given by the formula presented below, involving factorials.

In this problem, 4 captains are taken from a set of 13 + 13 + 10 + 16 = 52, hence the number of outcomes is:

The number of outcomes with four seniors is given as follows:

Hence the probability is:
p = 210/270725 = 0.0008.
With no seniors, the number of outcomes is:

Hence with at least one senior, the number of outcomes is:
270725 - 111930 = 158795.
Hence the probability is:
p = 158795/270725 = 0.5866.
With one of each, the number of outcomes is:
13 x 13 x 10 x 16 = 27040
Then the probability is:
27040/270725 = 0.0999.
With two sophomores and two freshmen, the number of outcomes is:

Then the probability is:
6084/270725 = 0.0225.
More can be learned about the combination formula at brainly.com/question/25821700
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