Question

Find the probability of each event. Answer IN FRACTION form.

A jar contains eight black buttons and five brown buttons. If eight buttons are picked at random, what is the probability that all of them are black?

Answer 1

= 8/6435

Explanation:

Number of black balls = 8

Number of Brown balls = 5

Total number of balls = 8+5 = 13

Pr (8 balls picked at random are black ) =

Number of black balls / Total number of balls.

1st Pr ( 8 balls picked are black) = 8/13

Pr (2nd random pick) = 7/12

Pr (3rd random pick) = 6/ 11

Pr (4th random pick) = 5/10

Pr (5th random pick) = 4/9

Pr (6th random pick) = 3/7

Pr (7th random pick) = 2/6

Pr (8th random pick) = 1/5

Pr (8 balls picked at random are black ) = 8/13 * 7/12 * 6/11 * 5/10 * 4/9 * 3/7 * 2/6 * 1/5

= 8/13 * 7/12 * 6/11 * 1/2 * 4/9 * 3/7 * 1/3 * 1/5

= 8/6435

But pls note, I solved it such that there wasn't a replacement after each pick.

Math is fun