Question

7. A box contains fifteen billiards balls, numbered 1 through 15. Anna draws a ball, records the number, and then returns it to the box. Then Vicki draws a ball. Find the probability of getting a 9 then a 3. *

Answer 1

0.0044 = 0.44%

Explanation:

If we have 15 balls, each one with a number from 1 to 15, and no number repeats, the probability of drawing a 9 is 1/15, as there is only one ball with number 9 inside the 15 balls.

After picking the first ball, it is returned, so we still have 15 balls with 15 differents numbers.

So, the probability of the second ball being number 3 is also 1/15 (just one ball with number 3 inside 15 balls)

So, the final probability is the product of each of these probabilities:

P = (1/15) * (1/15) = 1/225 = 0.0044 = 0.44%