Answer to Question #326182 in Statistics and Probability for Robera

Question

A ball is drawn at random from an urn containing one red and one white ball. If the

white ball is drawn, it is put back into the urn. If the red ball is drawn, it is returned to

the urn together with two more red balls. Then a second draw is made. What is the

probability a red ball was drawn on both the first and the second draws?

Answer 1

Probability of red ball at first round is 0.5.

Probability of red ball at second round is 3/4.

Then Probability of red ball at first and second round is 0.5x0.75=0.375