Using the combination formula, it is found that she can select the shirts in 775,200 ways.
The order in which the shirt are chosen is not important, hence, the combination formula is used to solve this question.
Combination formula:
[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:
[tex]T = C_{17,3} \times C_{20,3} = \frac{17!}{3!14!} \times \frac{20!}{3!17!} = 680 \times 1140 = 775200[/tex]
She can select the shirts in 775,200 ways.
To learn more about the combination formula, you can check https://brainly.com/question/25821700
