A drawer contains 12 white socks and 8 black socks. You randomly choose 1 sock and do not replace it. Then you randomly choose another sock.

Question

A drawer contains 12 white socks and 8 black socks. You randomly choose 1 sock and do not replace it. Then you randomly choose another sock.

 

Event A: The first sock is white.

Event B: The second sock is white.

 

Find the probability that both events A and B will occur. Round your answer to the nearest tenth.

 

its a %

Answer 1

12W, 8B

 

P(1st sock iw white) = 12/20 = 3/5 = 0.6

 

Now there are only 11 white socks left, and 8 black

 

P(2nd sock is white) = 11/19 = 0.5789...

 

P(1st and 2nd are white) = 0.6 x 0.5789... = 0.347368... = 0.3 to nearest tenth.

 

You can see this easily by drawing a tree diagram.