Question: You have three coins. One always comes up heads, one always comes up tails, and one is just a regular coin (has equal change of heads or tails). If you pick one of the coins randomly and flip it twice and get heads twice, what is the chance of flipping heads again?
Answer: 90 percent. If you pick the heads coin the chance of getting the first 2 heads is 100 percent (4/4) and if you pick the fair coin the chance is 25 percent (1/4). So from this, the chance that it is the heads coin is 4/5 and the fair coin 1/5.
Then, if it is the heads coin you will definitely get heads (4/5). If you flip the fair coin it is 1/10 (1/5 * 1/2). Add the probabilities together: 4/5 + 1/10 = 9/10.
Question: In a house of Kardak's family each brother have a sisters as double as their brothers and each sister have brothers as same as their sister. How many brothers and sisters in Kardak's family ?
Answer: 3 brothers and 4 sisters
Question: A traveler is walking in the jungle. Then he found 4 paths. In the first one has a really deep mud. When people go there, they never come back. Second path have broken tracks, which is really unsafe for the people who take this path. In the third path, there is lion who didn't eat and drink anything for 3 months, so it might be really hungry by now. Last one have dinosaurs and volcanoes, so it's a very dangerous place. So, which path is the best for the traveler to take.
Answer: The traveler should take the third one because the lion didn't have anything for 3 months right? If it actually didn't, it will be dead now. So, this path is the best to go.
Question: There were 2 doors. Behind the 1 door, is hell and behind the other door, is heaven but you don't know which door will take you to heaven. In front of them, there were 2 brothers, which is guarding the door. One of the brother always lie and the other one always tell the truth. Of course you don't know who is lying and who is not. You only get 1 question to ask one of them to figure out which door leads to heaven. What question you might ask? Remember you only get to ask 1 question. it means that you can't ask one question each of them. that will be 2 questions. You only ask 1 question to any of them and no more. How do you do that?
Answer: Go up to one of the guy and ask this question, " Hello, which door that your brother will point if I ask him which way is the heaven." Then take the other door. Don't enter the door that he was pointing. This question will work for both of them because if you ask this question to the truth guy, he will point the hell because he knows that his brother will point hell and if you asked to the liar, he'll still point hell because he knows that his brother will point to heaven door, so he lied. That's why you take the other door.