a bag contains 3 red balls and 2 blue balls. A ball is taken out at random and put back. A second ball is chosen and put back.
I've already drawn the tree diagram for this.
What is the probability of at least one red ball?
[Math] How do i calculate the probability of at least one red ball
probability
Best Answer
Both events are independent of each other. That is an important first step. Now notice that the probability of getting at least one red ball is the same as the probability of not having both blue balls, so our final probability will be 1 - P(drawing blue balls both times). P(drawing blue balls both times) is 2/5*2/5, which is 4/25, so your final probability will be 1 - 4/25 = 21/25