SOLUTION: Please help me with this question? If two marbles are selected from the bag without replacement, find the probability that: (i) the first marble is red and the second is white?

Algebra ->  Probability-and-statistics -> SOLUTION: Please help me with this question? If two marbles are selected from the bag without replacement, find the probability that: (i) the first marble is red and the second is white?       Log On


   

Question 829311: Please help me with this question? If two marbles are selected from the bag without replacement, find the probability that:
(i) the first marble is red and the second is white?
(ii) both marbles are red?
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Number of red marbles - N%5Br%5D
Number of white marbles - N%5Bw%5D
I assume there are only red and white marbles in the bag.
1.P%28r%29=%28N%5Br%5D%29%2F%28N%5Br%5D%2BN%5Bw%5D%29
P%28w%29=%28N%5Bw%5D%29%2F%28N%5Br%5D%2BN%5Bw%5D-1%29
So then,
P=P%5Br%5D%2AP%5Bw%5D
P=%28N%5Br%5D%2AN%5Bw%5D%29%2F%28%28N%5Br%5D%2BN%5Bw%5D%29%28N%5Br%5D%2BN%5Bw%5D-1%29%29
2.P%28r1%29=%28N%5Br%5D%29%2F%28N%5Br%5D%2BN%5Bw%5D%29
P%28r2%29=%28N%5Br%5D-1%29%2F%28N%5Br%5D%2BN%5Bw%5D-1%29
So then,
P=P%5Br1%5D%2AP%5Br2%5D