Bill and Stacie are delighted when their new baby, Patrick, is born on February 29th, 2008. They think it's good luck to for him to be born on the special day of the leap year. But then they start thinking about when to celebrate his next birthday. After some thought, they decide that they want to celebrate Patrick's next birthday (when he turns 1) exactly 365 days after he was born, just like most people do.
What will be the date of this birthday?
The date of the birthday will be February 28th, 2009.
At first it might seem like his birthday should be March 1st, 2009, since February 29th is the day after February 28th in the leap year, while March 1st is the day after February 28th in non-leap years. But this is the wrong way to think about it.
The right way to think about it is that 365 days after the day before March 1st is always February 28th, regardless of whether it's a leap year or not. So Patrick's birthday will be February 28th.
See also best riddles or new riddles.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.)cleanfunnylogicshort
Mary’s father has 5 daughters – Nana, Nene, Nini, Nono. What is the fifth daughters name?
If you answered Nunu, you are wrong. It’s Mary!logicprobability
Your enemy challenges you to play Russian Roulette with a 6-cylinder pistol (meaning it has room for 6 bullets). He puts 2 bullets into the gun in consecutive slots, and leaves the next four slots blank. He spins the barrel and hands you the gun. You point the gun at yourself and pull the trigger. It doesn't go off. Your enemy tells you that you need to pull the trigger one more time, and that you can choose to either spin the barrel at random, or not, before pulling the trigger again. Spinning the barrel will position the barrel in a random position.
Assuming you'd like to live, should you spin the barrel or not before pulling the trigger again?
You are better off shooting again without spinning the barrel.
Given that the gun didn't fire the first time, it was pointing to one of the four empty slots. Because your enemy spun the cylinder randomly, it would have been pointing to any of these empty slots with equal probability. Three of these slots would not fire again after an additional trigger-pull, and one of them would. Thus, by not spinning the barrel, there is a 1/4 chance that pulling the trigger again would fire the gun.
Alternatively, if you spin the barrel, it will point to each of the 6 slots with equal probability. Because 2 of these 6 slots have bullets in them, there would be a 2/6 = 1/3 chance that the gun would fire after spinning the barrel.
Thus, you are better off not spinning the barrel.interviewlogic
You are standing before two doors. One of the path leads to heaven and the other one leads to hell. There are two guardians, one by each door. You know one of them always tells the truth and the other always lies, but you don’t know who is the honest one and who is the liar. You can only ask one question to one of them in order to find the way to heaven. What is the question?
The question you should ask is “If I ask the other guard about which side leads to heaven, what would he answer?”. It should be fairly easy to see that irrespective of whom do you ask this question, you will always get an answer which leads to hell. So you can chose the other path to continue your journey to heaven.
This idea was famously used in the 1986 film Labyrinth.
Here is the explanation if it is yet not clear.
Let us assume that the left door leads to heaven.
If you ask the guard which speaks truth about which path leads to heaven, as he speaks always the truth, he would say “left”. Now that the liar , when he is asked what “the other guard (truth teller) ” would answer, he would definitely say “right”.
Similarly, if you ask the liar about which path leads to heaven, he would say “right”. As the truth teller speaks nothing but the truth, he would say “right” when he is asked what “the other guard( liar ) ” would answer. So in any case, you would end up having the path to hell as an answer. So you can chose the other path as a way to heaven.cleanlogic
Three people check into a hotel. They pay $30 to the manager and go to their room. The manager finds out that the room rate is $25 and gives $5 to the bellboy to return. On the way to the room, the bellboy reasons that $5 would be difficult to share among three people, so he pockets $2 and gives $1 to each person. Now, each person paid $10 and got back $1. So they paid $9 each, totalling $27. The bellboy has $2, totalling $29. )
Where is the remaining dollar?
Each person paid $9, totalling $27. The manager has $25 and the bellboy has $2. The bellboy's $2 should be added to the manager's $25 or substracted from the tenant's $27, not added to the tenants' $27.logic
Which month has 30 days?
All of them, except February.cleanfunnylogic
After recent events, Question Mark is annoyed with his brother, Skid Mark. Skid thought it would be funny to hide Question's wallet. He told Question that he would get it back if he finds it. So, first off, Skid laid five colored keys in a row. One of them is a key to a room where Skid is hiding Question's wallet. Using the clues, can you determine the order of the keys and which is the right key?
Red: This key is somewhere to the left of the key to the door.
Blue: This key is not at one of the ends.
Green: This key is three spaces away from the key to the door (2 between).
Yellow: This key is next to the key to the door. Orange: This key is in the middle.
The order (from left to right) is Green, Red,Orange, Blue, Yellow. The blue key is the key to the door.cleanlogicmystery
Alexander is stranded on an island covered in forest.
One day, when the wind is blowing from the west, lightning strikes the west end of the island and sets fire to the forest. The fire is very violent, burning everything in its path, and without intervention the fire will burn the whole island, killing the man in the process.
There are cliffs around the island, so he cannot jump off. How can the Alexander survive the fire? (There are no buckets or any other means to put out the fire)
Alexander picks up a piece of wood and lights it from the fire on the west end of the island. He then quickly carries it near the east end of he island and starts a new fire. The wind will cause that fire to burn out the eastern end and he can then shelter in the burnt area. Alexander survives the fire, but dies of starvation, with all the food in the forest burnt.cleanlogicshortwhat am I
I have billions of eyes, yet i live in darkness. I have millions of ears, yet only four lobes. I have no muscle, yet i rule two hemispheres. What am I?
I am the human brain. The brain has billions of optic and auditory nerves, four lobes and two hemispheres, and is an organ of the human body.logic
You have twelve balls, identical in every way except that one of them weighs slightly less or more than the balls.
You have a balance scale, and are allowed to do 3 weighings to determine which ball has the different weight, and whether the ball weighs more or less than the other balls.
What process would you use to weigh the balls in order to figure out which ball weighs a different amount, and whether it weighs more or less than the other balls?
Take eight balls, and put four on one side of the scale, and four on the other.
If the scale is balanced, that means the odd ball out is in the other 4 balls.
Let's call these 4 balls O1, O2, O3, and O4.
Take O1, O2, and O3 and put them on one side of the scale, and take 3 balls from the 8 "normal" balls that you originally weighed, and put them on the other side of the scale.
If the O1, O2, and O3 balls are heavier, that means the odd ball out is among these, and is heavier. Weigh O1 and O2 against each other. If one of them is heavier than the other, this is the odd ball out, and it is heavier. Otherwise, O3 is the odd ball out, and it is heavier.
If the O1, O2, and O3 balls are lighter, that means the odd ball out is among these, and is lighter. Weigh O1 and O2 against each other. If one of them is lighter than the other, this is the odd ball out, and it is lighter. Otherwise, O3 is the odd ball out, and it is lighter.
If these two sets of 3 balls weigh the same amount, then O4 is the odd ball out. Weight it against one of the "normal" balls from the first weighing. If O4 is heavier, then it is heavier, if it's lighter, then it's lighter.
If the scale isn't balanced, then the odd ball out is among these 8 balls.
Let's call the four balls on the side of the scale that was heavier H1, H2, H3, and H4 ("H" for "maybe heavier").
Let's call the four balls on the side of the scale that was lighter L1, L2, L3, and L4 ("L" for "maybe lighter").
Let's also call each ball from the 4 in the original weighing that we know aren't the odd balls out "Normal" balls.
So now weigh [H1, H2, L1] against [H3, L2, Normal].
-If the [H1, H2, L1] side is heavier (and thus the [H3, L2, Normal] side is lighter), then this means that either H1 or H2 is the odd ball out and is heavier, or L2 is the odd ball out and is lighter.
-So measure [H1, L2] against 2 of the "Normal" balls.
-If [H1, L2] are heavier, then H1 is the odd ball out, and is heavier.
-If [H1, L2] are lighter, then L2 is the odd ball out, and is lighter.
-If the scale is balanced, then H2 is the odd ball out, and is heavier.
-If the [H1, H2, L1] side is lighter (and thus the [H3, L2, Normal] side is heavier), then this means that either L1 is the odd ball out, and is lighter, or H3 is the odd ball out, and is heavier.
-So measure L1 and H3 against two "normal" balls.
-If the [L1, H3] side is lighter, then L1 is the odd ball out, and is lighter.
-Otherwise, if the [L1, H3] side is heavier, then H3 is the odd ball out, and is heavier.
If the [H1, H2, L1] side and the [H3, L2, Normal] side weigh the same, then we know that either H4 is the odd ball out, and is heavier, or one of L3 or L4 is the odd ball out, and is lighter.
So weight [H4, L3] against two of the "Normal" balls.
If the [H4, L3] side is heavier, then H4 is the odd ball out, and is heavier.
If the [H4, L3] side is lighter, then L3 is the odd ball out, and is lighter.
If the [H4, L3] side weighs the same as the [Normal, Normal] side, then L4 is the odd ball out, and is lighter.