Question

An urn contains 7 pink and 5 black balls. Four 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 pink? Round your answer to three decimal places.

Answer 1

.116

Explanation:

7 pink and 5 black balls. = 12 balls

P( pink) = pink balls/ total = 7/12

replace

P( pink) = pink balls/ total = 7/12

so this is true for each case

P( pink, pink, pink, pink) = 7/12*7/12*7/12*7/12 = 2401/20736

=.115788966

To 3 decimal places

.116