A man decides to buy a nice horse. He pays $600 for it and he is very content with this strong animal. After a year the value of the horse has increased to $700 and he decides to sell the horse. But a few days later he regrets his decision so he buys back the horse again. Unfortunately he has to pay $800 to get it back so he loses $100. After another year of owning the horse he finally decides to sell the horse for $900. What is the overall profit the man makes?

A boy was carrying a basket of eggs. He fell down and all the eggs broke. When he went back home without any eggs his mother asked how many he had been carrying altogether in the basket. He was unable to remember. But he was able to recall that when they were counted two at a time one was left, when counted three at a time one was left, when counted four at a time one was left, when counted five at a time none were left. Can you tell how many eggs were broken?

Jack is a farmer and owns a chicken farm. One day, he took a basket of fresh eggs to the market to sell. The first person bought half of all the eggs in the basket and half an egg. Then, the second person bought half of the remaining eggs and half an egg. Later, the third person bought half of the remaining eggs and half an egg. Now Jack’s basket has only 1 egg left. If no eggs were broken in the process, how many eggs did he originally have in his basket?

Two trains travel toward each other on the same track, beginning 100 miles apart. One train travels at 40 mph (miles per hour); the other travels at 60 mph. A bird starts flight at the same location as the faster train, flying at a speed of 90 mph. When it reaches the slower train, it turns around, flying the other direction at the same speed. When it reaches the faster train again, it turns around, and so on. When the trains meet, how far will the bird have flown?

Johnny is walking home. He has $300 to bring home to his mom. While he is walking, a man stops him and gives him a chance to double his money. The man says, “I’ll give you $600 if you can roll 1 die and get a 4 or above, you can roll 2 dice and get a 5 or 6 on at least one of them, or you can roll 3 dice and get a 6 on at least one die. If you don’t I get your $300.” What does Johnny do to have the best chance of getting home with the money?

You were captured and given one chance to escape with your life. You’re forced to play Russian Roulette with a 6-cylinder pistol. Each cylinder can hold 1 bullet. The gun has 2 bullets in it and the rounds were placed consecutively and the barrel was spun. You took one shot and heard the click, luckily you didn’t get a bullet. You can choose to spin the barrel before the next shot. You want to live. Should you spin the barrel to improve your chances of survival?

Two schoolgirls were traveling from the city to a dacha (summer cottage) on an electric train. “I notice,” one of the girls said, “that the dacha trains coming in the opposite direction pass us every 5 minutes. What do you think-how many dacha trains arrive in the city in an hour, given equal speeds in both directions?” “Twelve, of course,” the other girl answered, “because 60 divided by 5 equals 12.” The first girl did not agree. What do you think?

Four people need to cross a rickety rope bridge to get back to their camp at night. Unfortunately, they only have one flashlight and it only has enough light left for seventeen minutes. The bridge is too dangerous to cross without a flashlight, and it’s only strong enough to support two people at any given time. Each of the campers walks at a different speed. One can cross the bridge in 1 minute, another in 2 minutes, the third in 5 minutes, and the fourth takes 10 minutes to cross. How do the campers cross the bridge in 17 minutes?

Every man in a village of 100 married couples has cheated on his wife. Every wife in the village instantly knows when a man other than her husband has cheated, but does not know when her own husband has. The village has a law that does not allow for adultery. Any wife who can prove that her husband is unfaithful must kill him that very day. The women of the village would never disobey this law. One day, the queen of the village visits and announces that at least one husband has been unfaithful. Everyone knows that the queen only speaks the truth. What happens?

A man goes into a barber shop and gets a haircut for $15. He pays the barber with a $20 bill, but the barber doesn’t have change. The barber goes to the neighboring flower shop and trades the $20 bill for a $10 dollar bill and two $5 bills. Then he gives the man his $5 in change. Later the lady from the flower shop confronts the barber and tells him that the $20 bill he gave her was counterfeit money. The barber agrees and he gives the lady a different $20 bill. Later that day he tries to figure out how much money he lost. How much money did the barber lose?

Tim and Pat were engaged by the local authorities to paint the lamp posts in a certain street. Tim, who was an early riser, arrived first on the job, and had painted three on the south side when Pat turned up and pointed out that Tim’s contract was for the north side. So Tim started afresh on the north side and Pat continued on the south. When Pat had finished his side he went across the street and painted six posts for Tim, and then the job was finished. There were an equal number of lamp-posts on each side of the street. Who painted more lamp posts, and how many more?

You are given two eggs, and access to a 100-storey building. Both eggs are identical. The aim is to find out the highest floor from which an egg will not break when dropped from a floor. If an egg is dropped and does not break, it is undamaged and can be dropped again. However, once an egg is broken, it cannot be used anymore. If an egg breaks when dropped from floor N, then it would also have broken from any floor above that. If an egg survives a fall from floor N, then it will also survive any fall below floor N. What is the minimum number of egg drops required to find the solution?

During certain local floods five married couples found themselves surrounded by water, and had to escape from their unpleasant position in a boat that would only hold three persons at a time. Every husband was so jealous that he would not allow his wife to be in the boat or on either bank with another man (or with other men) unless he was himself present. Show the quickest way of getting these five men and their wives across into safety. Call the men A, B, C, D, E, and their respective wives a, b, c, d,e. To go over and return counts as two crossings. No tricks such as ropes, swimming, currents, etc., are permitted.

Albert and Bernard became friends with Cheryl, and they want to know when her birthday is. Cheryl gives them a list of 10 possible dates. May 15 May 16 May 19 June 17 June 18 July 14 July 16 Aug 14 Aug 15 Aug 17 Cheryl then tells Albert and Bernard separately the month and the day of her birthday respectively. Albert: I don’t know when Cheryl’s birthday is, but I know that Bernard does not know too. Bernard: At first I don’t know when Cheryl’s birthday is, but I know now. Albert: Then I also know when Cheryl’s birthday is. When is Cheryl’s birthday?

A professor asked John to write down any multi-digit number. But, he put a condition, the number should not end with a zero. John put down the number 96452. Then the professor asked John to add up the five digits and subtract the total from the original number. John did and here is what he got: 96452 – 26 = 96426 The professor then asked John to cross out any one of the five digits and tell him the remaining numbers. John crossed out the 2 and told the professor the rest of the digits. John neither told the professor the original number nor what he had done with it. Yet, the professor told John the exact number he had crossed out. How is it possible?