There are 3 black marbles and 4 red marbles in a bag.
What is the probability of picking a black marble, replacing it back in the bag, and then choosing another black marble?
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 [tex]P(A_2)=\dfrac{3}{7}[/tex] Together: [tex]P(A)=P(A_1)\cdot P(A_2)=\dfrac{3}{7}\cdot\dfrac{3}{7}=\dfrac{9}{49}\to 2)[/tex]
