In the urn, 15 white and 6 black balls take out one ball for guessing, return it to the urn and mix the balls.

In the urn, 15 white and 6 black balls take out one ball for guessing, return it to the urn and mix the balls. Then take out the second ball. What is the probability that both balls taken out are white?

15 – white balls;

6 – black balls.

15 + 6 = 21 – total balls;

15/21 = 5/7 – the probability that the 1st ball will be white;

15/21 = 5/7 – the probability that the 2nd ball will be white;

5/7 * 5/7 = 25/49 – the probability that both balls will be white.

25/49 = 0.51.

0.51 * 100% = 51% – the probability that both balls will be white.

Answer: 51% that both balls will be white.