Using the combination formula, it is found that the probability that she will choose one by each composer is given by:
144/1365.
[tex]C_{n,x}[/tex] is the number of different combinations of x objects from a set of n elements, given by:
[tex]C_{n,x} = \frac{n!}{x!(n-x)!}[/tex]
In this problem, she will pick 4 CDs from a set of 4 + 6 + 3 + 2 = 15, hence the total number of options is given by:
[tex]C_{15,4} = \frac{15!}{4!11!} = 1365[/tex]
The number of options that include one from each is given by:
N = 4 x 6 x 3 x 2 = 144.
Hence the probability is given by:
p = 144/1365.
More can be learned about the combination formula at https://brainly.com/question/25821700
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