Question

An urn contains 6 red and 7 black balls. 4 balls are randomly drawn from the urn in succession, with replacement. That is after each draw, the selected ball is returned to the urn. What is the probability that all 4 balls drawn from the urn are black ? Round your answer to three decimal places.

Answer 1

0.538

Explanation:

There are 13 balls in the urn

• 7 are black and 6 are red

There are 7 chances out of 13 to pick a black ball

• 7/13
• 7 ÷ 13 = 0.53846.....

Round and get:

• 0.538