Question 765991: What is the probability that a random 2-digit number (00-99) does not end in 3?
What is the probability that a randomly selected date in one year is not in the month of December or January?
There are 12 ballons in a bag: 3 each of blue, green, red, and yellow. Three balloons are chosen at random. Find the probability that all 3 balloons are green.
A coach randomly selects 3 swimmers from a team of 8 to swim in a heat. What is the probability that the three strongest swimmers are chosen?
There are 7 books numbered 1 through 7 on the summer reading list. Peter randomly chooses two books. What is the probability that he chose books 1 and 4?
Found 2 solutions by solver91311, MaartenRU:
Answer by solver91311(24713)   (Show Source):
You can put this solution on YOUR website!
What is the probability that you are going to get help on this website if you don't follow the written instructions for posting, e.g. "One question per post"?
John
Egw to Beta kai to Sigma
My calculator said it, I believe it, that settles it
Answer by MaartenRU(13)  (Show Source):
You can put this solution on YOUR website! 1) There are 100 possible choices: the numbers 0, 1, ..., 98, 99. Now, of those, there are 10 that end in 3: 03, 13, ..., 83, 93. So the probability of choosing one of those is 10/100, or 1/10. So the probability of *not* choosing one of those is the complement of that, or what is left if you subtract it from 1: 
2) Let's assume that we can ignore leap years here. There are 365 days in a year, and 31+31=62 days in January and December. The probability of choosing a day in those months is 62/365, so the probability of *not* choosing one of those is, you guessed it, the complement: 
3) The first time we pick a balloon, we have a 3/12 chance of picking a green one. If we then assume we already have taken one, there are 2 green balloons left, and 11 in total. So the probability of us picking another green one will be 2/11. In the same way the probability of picking a green one the third time around will be 1/10. So our probability of picking three green balloons in a row is 
4) The same idea as the previous question. The first time, the probability of picking one of the best 3 swimmers is 3/8. The second time, one of them can't be chosen anymore, and there is one less swimmer, so 2/7. The third time it's 1/6. So the total probability will be 
5) Once more. The probability of choosing one of those books at the start is 2/7. Then Peter needs to pick the other one out of 6 remaining books, so 1/6. The total amounts to 
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