10 + 5 + 1 = 16 - all balls
The probability that the first ball is red:
[tex]P(R)=\dfrac{10}{16}=\dfrac{5}{8}[/tex]
The probability that the second ball is black:
[tex]P(B)=\dfrac{1}{15}[/tex]
Together:
[tex]P(R)\cdot P(B)=\dfrac{5}{8}\cdot\dfrac{1}{15}=\dfrac{1}{24}[/tex]
