Answer: B. 350.
Step-by-step explanation:
Given: Total number of fluorescent colors = 7
Total number of pastel colors = 5
Since , he want three fluorescent colors and two pastel colors.
Number of ways to select r things out of n things = [tex]^nC_r=\dfrac{n!}{r!(n-r)!}[/tex]
Number of ways to choose colors = [tex]^7C_3\times\ ^5C_2[/tex]
[tex]=\dfrac{7!}{3!4!}\times\dfrac{5!}{2!3!}\\\\=\dfrac{7\times6\times5\times4!}{3\times2\times1\times4!}\times\dfrac{5\times4\times3!}{2\times3!}\\\\=350[/tex]
Hence, the correct option is B. 350.
