There are 3 black marbles and 4 red marbles in a bag.
What is the probability you will pick two black marbles out of the bag without replacing the first one chosen?
3 + 4 = 7 all marables in bag The probability that the first marable is black [tex]P(A_1)=\dfrac{3}{7}[/tex] The probability that the second marable is black too [tex]P(A_2)=\dfrac{2}{6}=\dfrac{1}{3}[/tex] Together: [tex]P(A)=P(A_1)\cdot P(A_2)=\dfrac{3}{7}\cdot\dfrac{1}{3}=\dfrac{1}{7}\to D[/tex]
