SOLUTION: 7 cards are marked with a diferent number from 1-7, then placed face down on a table. One card is selected at random and not placed. A second card is then taken, at random . Determ

Algebra ->  Probability-and-statistics -> SOLUTION: 7 cards are marked with a diferent number from 1-7, then placed face down on a table. One card is selected at random and not placed. A second card is then taken, at random . Determ      Log On


   

Question 646776: 7 cards are marked with a diferent number from 1-7, then placed face down on a table. One card is selected at random and not placed. A second card is then taken, at random . Determine the probabity that one card has an odd number on it.
This is the question I am unsure about. I found out that the probability for the first card that is picked up is 4/7 and for the second card the probability is 3/6 but I am not sure how to then use that info to get an answer to the writing above? Could you help?
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi,

7 cards, 4 with odd numbers

draw 1 w/o replacement and draw another 

P(one odd) = 4C1%2A3C1%2F7C2+=+12%2F21+=+4%2F7  

OR 

4/7*3/6 + 3/7*4/6 = 12/42 + 12/42 = 24/42 = 4/7