You have two jugs, one that holds exactly 3 gallons, and one that holds exactly 5 gallons. Using just these two jugs and a fire hose, how can you measure out exactly 4 gallons of water?
Fill the 5-gallon jug to the top, and then pour it into the 3-gallon jug until the 3-gallon jug is full. You now have 2 gallons remaining in the 5-gallon jug. Pour out the 3-gallon jug, and then pour the 2 gallons from the 5-gallon jug into the 3-gallon jug. Finally, fill the 5-gallon jug to the top and pour it into the 3-gallon jug until it's full. Since there was only space left for 1 more gallon in the 3-gallon jug, you now have exactly 4 gallons in the 5-gallon jug.
See also best riddles or new riddles.logic
You've been placed on a course of expensive medication in which you are to take one tablet of Sildenafil and one tablet of Citrate daily. You must be careful that you take just one of each because taking more of either can have serious side effects. Taking Sildenafil without taking Citrate, or vice versa, can also be very serious, because they must be taken together in order to be effective. In summary, you must take exactly one of the Sildenafil pills and one of the Citrate pills at one time. Therefore, you open up the Sildenafil bottle, and you tap one Sildenafil pill into your hand. You put that bottle aside and you open the Citrate bottle. You do the same, but by mistake, two Citrates fall into your hand with the Sildenafil pill. Now, here's the problem. You weren't watching your hand as the pills fell into it, so you can't tell the Sildenafil pill apart from the two Citrate pills. The pills look identical. They are both the same size, same weight (10 micrograms), same color (Blue), same shape (perfect square), same everything, and they are not marked differently in any way. What are you going to do? You cannot tell which pill is which, and they cost $300 a piece, so you cannot afford to throw them away and start over again. How do you get your daily dose of exactly one Sildenafil and exactly one Citrate without wasting any of the pills?
Carefully cut each of the three pills in half, and carefully separate them into two piles, with half of each pill in each pile. You do not know which pill is which, but you are 100% sure that each of the two piles now contains two halves of Cirate and half of Sildenafil. Now go back into the Sildenafil bottle, take out a pill, cut it in half, and add one half to each stack. Now you have two stacks, each one containing two halves of Sildenafil and two halves of Citrate. Take one stack of pills today, and save the second stack for tomorrow. logicshort
Finish the sequence:
7 8 5 5 3 4 4 ?
6 - the number of letters in the month august; (January has 7 letters, February has 8 etc.)logicmathshort
Using eight eights and addition only, can you make 1000?
888 + 88 + 8 + 8 + 8 = 1000logicmystery
There once was an evil wizard. He took 3 women from their homes and turned them into rose bushes that looked exactly alike. He put them in his garden. One of the women had a husband and children and begged the wizard to let her see them. He agreed. At night he brought the woman to her house. In the morning he came and took her home. Next day the husband decided to go rescue her. So he snuck into the wizard's garden. He looked and looked at the 3 identical rose bushes trying to figure out which could be his wife. Suddenly he knew the answer and he took his wife home. How did he know which rose bush was his wife?
The wizard brought the rosebush to her home at night and returned her to the garden in the morning. Therefore, she was the only plant without dew.cleanlogicshortwhat am I
Give me food, and I will live. Give me water, and I will die. What am I?
It is greater than god, more evil than the devil, the poor have it, the rich need it, and if you eat it, you will die? What is it?
A cat had three kittens: January, March and May. What was the mother's name?
It is stated 'WHAT' was the mother's name.logicprobability
Your friend shows you two jars, one with 100 red marbles in it, the other with 100 blue marbles in it.
He proposes a game. He'll put the two jars behind his back and tell you to pick one of them at random. You'll then close your eyes, he'll hand you the jar you picked, and you'll pick a random marble from that jar.
You win if the marble you pick is blue, and you lose otherwise.
To give you the best shot at winning, your friend gives you the two jars before the game starts and says you can move the marbles around however you'd like, as long as all 200 marbles are in the 2 jars (that is, you can't throw any marbles away).
How should you move the marbles around to give yourself the best chance of picking a blue marble?
Put one blue marble in one jar, and put the rest of the marbles in the other jar. This will give you just about a 75% chance of picking a blue marble.cleanlogicshort
What 8 letter word can have a letter taken away and it still makes a word. Take another letter away and it still makes a word. Keep on doing that until you have one letter left. What is the word?
The word is starting! starting, staring, string, sting, sing, sin, in, i. logicmystery
The Smith family is a very wealthy family that lives in a big, circular home. One morning, Mr. Smith woke up and saw a strawberry jam stain on his new carpet. He figured out that everyone who was there that morning had a jam sandwich. By reading the following excuses, figure out who spilled the jam.
Billy Smith: "I was outside playing basketball."
The Maid: "I was dusting the corners of the house."
Chef: "I was starting to make lunch for later."
Who is lying?
It was the maid. The house is circular, it has no corners.