SOLUTION: In a bag there are 20 red marbles and 15 black ones. By no replacement, find the probability that randomly selecting four marbles, they are all red.

Algebra ->  Probability-and-statistics -> SOLUTION: In a bag there are 20 red marbles and 15 black ones. By no replacement, find the probability that randomly selecting four marbles, they are all red.      Log On


   

Question 309422: In a bag there are 20 red marbles and 15 black ones. By no replacement, find the probability that randomly selecting four marbles, they are all red.
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
20 R, red
15 B, black
35 total to start
P(R)=20/35=4/7
w/o replacement
P(R)=19/34
w/o replacement
P(R)=18/33=6/11
w/o replacement
P(R)=17/32
Multiply the probabilities,
P(R,R,R,R)=(4/7)(19/34)(6/11)(17/32)
P(R,R,R,R)=(19*3)/(7*2*11*4)
P(R,R,R,R)=57/616