Probability

Bertrins box. You have three cabinets. Each of these three cabinets has two drawers. In one of the cabinets, there is a Gold coin in one drawer and a silver in the other. In another there is a gold coin in both drawers. In the last cabinet there is a silver coin in each drawer. Now you walk into the room, not knowing the location of any of the coins, and pick a gold coin in one of the drawers. Now, what is the probability that the other drawer in the same cabinet contains a gold coin?	Answer 19
Bag of Marbles There were two identical bags (not see through) each containing two marbles. One bag had two red marbles and the other had a red and a blue marble. The question asked was: if you put your hand and draw out a red marble from one of the bags, what is the probability that the other marble in that the next marble drawn from the chosen bag will be red?	Answer 19
The right chair 50 people attending a conference decide to go out for a drink. Most of them drink tea, but one person drinks a bit too much whiskey. They all return to the conference room and go back to their own seats, one by one. The slightly intoxicated person can't remember his place, and sits down on a random chair. If the owner of that chair comes along he can't sit there and he, too, will have to choose another chair at random. The intoxicated person is not the last one to enter the room. Question: What is the chance that the last person to sit down will sit in the right chair?	Answer 19
Both Girls? If a person has two children, and truthfully answers yes to the question "Is at least one of your children a girl?", what is the probability that both children are girls?	Answer 19
Oldest Girl? You meet an old friend on the street, and ask how many children he has. He truthfully says two. You ask "Is the older one a girl?" He truthfully says yes. What is the probability that both children are girls? What would the probability that both children are girls be, if he truthfully says yes, to your second question; "Is at least one of them a girl?"	Answer 19
Two Dice You throw a pair of dice while blindfolded. You are informed that one of the dice landed showing two. What is the probability that the other die also shows two?	Answer 19
Arms What is the probability that the next person you see will have an above average number of arms: a) Zero b) Highly unlikely c) Almost certain d) Certain	Answer 19
10 playing cards Five red and five black playing cards are shuffled and dealt face-down. If you draw two cards, what are your chances of getting two of the same colour?	Answer 19
Monty Hall You are a participant on "Let's Make a Deal". Monty Hall shows you three closed doors. He tells you that two of the closed doors have a goat behind them and that one of the doors has a new car behind it. You pick one door, but before you open it Monty opens one of the two remaining doors and shows that it hides a goat. He then offers you a chance to switch doors with the remaining closed door. Is it to your advantage to do so?	Answer 19
Vowels The chances that all vowels (a, e, i, o and u) would have had this similarity were less than 2%. Can you identify which simularity?	Answer 19
Coin flip If you flip a coin 10 times, what are the odds to have ten heads in a row. If you flip a coin 11 times. If you flip 12 times...?	Answer 19
Throwing Darts You are blind and have three arrows and you throw at a dartboard that has three areas of equal size and form. The three areas have a value of 1, 4 and 7, which can form 7 different total scores. Assume you always hit the board. What is your chance of throwing a total score (with three arrows) that forms a prime number.	Answer 19
Two jars. I have two jars. Jar #1 has 12 balls, 5 red, 7 blue. Jar #2 has 19 balls, 7 red, 12 blue. A ball is blindly chosen at random from jar #1 and placed in jar #2. Then A ball is chosen from jar #2. What is the probability that it is red? Given that it is red, what is the probability that the first ball removed from jar #1 was blue?	Answer 19
Tickets in a Box. I have 70 numbered tickets (1 to 70) in a box. 1. If I take out 5 tickets, what is the probability that all five tickets came out in ascending order? 2. What if I had 5 unique numbered tickets in a box and I took out all five?	Answer 19
Four Jawbreakers. "Your friend has four jawbreakers -- 2 green, 1 purple, and 1 yellow. She draws 2 of them out of a bag and shows you one of them, which is green. What is the probability that the other ball is also green?"	Answer 19
Blue & red marbles. You have two jars, 50 red marbles and 50 blue marbles. A jar will be picked at random, and then a marble will be picked from the jar. Placing all of the marbles in the jars, how can you maximize the chances of a red marble being picked? What are the exact odds of getting a red marble using your scheme?	Answer 19

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