Question 468970: There are 5 red and 4 black balls in a box. If you pick out 3 balls without replacement, what is the probability of getting red, black,then red in that order? Round to the nearest thousandth.
Any help on this would be much appreciated, thank you.
Answer by kingme18(98)   (Show Source):
You can put this solution on YOUR website! Since there are 5 red and 4 black, you're starting with 9 balls. The probability of getting a red one is 5/9 (there are 5 reds out of the 9 total possibilities). You're not replacing, so set that one aside. Now, you have 4 red and 4 black, for a total of 8 balls. The probability of getting black right now is 4/8 (there are 4 black out of the 8 total possibilities). Set that one aside. Now, you have 4 red and 3 black, for a total of 7 balls. The probability of getting a red one is 4/7 (4 reds out of 7 total).
To calculate the overall probability, we multiply. (We want the probability that the first AND second AND third event occurred, so it's multiplication; if we wanted the probability of one situation OR another situation, we'd add.)
|
|
|
