Brain Teasers Activate Mind Potential - Brain Teasers Page 1

Brain Teasers Activate Mind Potential

No.1	By moving one of the following digits, make the sum correct. 62 - 63 = 1	Solution 2⁶ - 63 = 1 (In other words, 2x2x2x2x2x2, which equals 64)
No.2	You have a fox, a chicken and a sack of grain. You must cross a river with only one of them at a time. If you leave the fox with the chicken he will eat it; if you leave the chicken with the grain he will eat it. How can you get all three across safely?	Solution Take the chicken over first. Go back and bring the grain next, but instead of leaving the chicken with the grain, come back with the chicken. Leave the chicken on the first side and take the fox with you. Leave it on the other side with the grain. Finally, go back over and get the chicken and bring it over.
No.3	You have 12 black socks and 12 white socks mixed up in a drawer. It's early in the morning and you don't have any light to see the colors. How many socks must you pull out (blindly) to be sure of getting a matching pair?	Solution 3 socks. If the first sock is black, the second one could be black, in which case you have a matching pair. If the second sock is white, the third sock will be either black and match the first sock, or white and match the second sock.
No.4	What is special about the following sequence of numbers? 8 5 4 9 1 7 6 10 3 2 0	Solution The numbers are in alphabetical order. (eight, five, four, nine, one, seven, six, ten, three, two, zero)
No.5	Three travelers register at a hotel and are told that their rooms will cost $10 each so they pay $30. Later the clerk realizes that he made a mistake and should have only charged them $25. He gives a bellboy $5 to return to them but the bellboy is dishonest and gives them each only $1, keeping $2 for himself. So the men actually spent $27 and the bellboy kept $2 - what happened to the other dollar of the original $30?	Solution Nothing. The 3 travelers paid a total of $27, making $25 for the hotel and $2 for the clerk. There is no missing $1.
No.6	You are the bus driver. At your first stop, you pick up 29 people. On your second stop, 18 of those 29 people get off, and at the same time 10 new passengers arrive. At your next stop, 3 of those 10 passengers get off, and 13 new passengers come on. On your fourth stop 4 of the remaining 10 passengers get off, 6 of those new 13 passengers get off as well, then 17 new passengers get on. What is the color of the bus driver's eyes?	Solution The eye color of the reader of this problem. The first sentence is the key: "You are the bus driver"
No.7	A rooster lays an egg at the very top of a slanted roof. Which side is the egg going to roll off on?	Solution Neither, roosters don't lay eggs.
No.8	Why is it very common to have a 9 minute snooze interval on alarm clocks, why not 10 instead?	Solution By setting the snooze time to 9 minutes, the alarm clock only needs to watch the last digit of the time. So, if you hit snooze at 6.45, the alarm goes off again when the last digit equals 4. They couldn't make it 10 minutes, otherwise the alarm would go off right away, or it would take more circuitry.
No.9	A bookworm eats from the first page of an encyclopedia to the last page. The bookworm eats in a straight line. The encyclopedia consists of ten 1000-page volumes and is sitting on a bookshelf in the usual order. Not counting covers, title pages, etc., how many pages does the bookworm eat through?	Solution 1. On a book shelf the first page of the first volume is on the "inside" 2. __ __ 3. B\| \| \| \|F 4. A\|1 \|.....\|10\|R 5. C\| \| \| \|O 6. K\| \| \| \|N 7. \| \| \| \|T 8. ------------- so the bookworm eats only through the cover of the first volume, then 8 times 1000 pages of Volumes 2 - 9, then through the cover to the 1st page of Vol 10. He eats 8,000 pages.
No.10	An Arab sheikh tells his two sons to race their camels to a distant city to see who will inherit his fortune. The one whose camel is slower will win. The brothers, after wandering aimlessly for days, ask a wise man for advise. After hearing the advice they jump on the camels and race as fast as they can to the city. What does the wise man say?	Solution The wise man tells them to switch camels.
No.11	An 18-wheeler is crossing a 4 kilometer bridge that can only support 10,000 kilograms and that's exactly how much the rig weighs. Halfway across the bridge a 30 gram sparrow lands on the cab, but the bridge doesn't collapse. Why not?	Solution Since the bridge is 4 kilometers long, the halfway point would be 2 kilometers. The 18-wheeler would have used much more than 30g of fuel to drive 2 kilometers.
No.12	A completely black dog was strolling down Main Street during a total blackout affecting the entire town. Not a single streetlight had been on for hours. Just as the dog was crossing the middle line a Buick Skylark with 2 broken headlights speedily approaches his position, but manages to swerve out of the way just in time. How could the driver have possibly seen the dog to swerve in time?	Solution It was during the day
No.13	In a small cabin in the woods, two men lay dead. The cabin itself is not burned, but the forest all around is burned to cinders. How did the men die?	Solution It's the cabin of a plane and the plane crashed.
No.14	Ida puts her coffee into the microwave, as she does every morning, for exactly 2 minutes. When the microwave goes off, she opens the door, but then closes the door again and sets the microwave for 2 more seconds. What good would 2 more seconds be?	Solution To rotate the handle on the mug so she can comfortably remove it.
No.15	Beulah died in the Appalachians while Craig died at sea. Everyone was much happier with Craig's death. Why?	Solution Beulah and Craig were hurricanes.
No.16	You are a cook in a remote area with no clocks or other way of keeping time other than a four minute sandglass timer and a seven minute sandglass timer. (The kind you turn over - hourglass shaped) You do have a stove, however, with water in a pot already boiling. Somebody asks you for a nine-minute egg, and you know this person is a perfectionist and will be able to tell if you undercook or overcook the eggs by even a few seconds. What is the least amount of time it will take to prepare the egg? And how will you prepare it so that it is neither undercooked nor overcooked?	Solution The answer is 9 minutes. First, flip both hourglasses over and drop the egg into the water. When the four minute timer runs out, flip it again. When the seven minute timer runs out, flip it over. The egg has been cooking seven minutes. Now when the four minute timer runs out again (after eight minutes) flip the seven minute timer back over. Since the seven minute timer has been running only a minute between flips, there's a minute worth of sand left. And when that minute runs out, the egg will have been cooking for exactly nine minutes.
No.17	I am the owner of a pet store. If I put in one canary per cage, I have one bird too many. If I put in two canaries per cage, I have one cage too many. How many cages and canaries do I have?	Solution Four canaries and three cages. If you put one canary in each cage, you have an extra bird without a cage. However, if you put two canaries in each cage then you have two canaries in the first cage, two canaries in the second cage and an extra cage.
No.18	Here is a series of numbers. What is the next number in the sequence? 1 11 21 1211 111221 312211 13112221	Solution The next number in the sequence is 1113213211, because the rule for creating the next number is to simply describe the previous number. For example, you start of with 1, with is simply one 1, so the next number is 11. Now you have two 1's, so the next number is 21. Now you have one 2 and one 1, so the next number is 1211. The solution is to simply continue describing the previous number using only numbers.
No.19	My daughter has many sisters. She has as many sisters as she has brothers. Each of her brothers has twice as many sisters as brothers. How many sons and daughters do I have?	Solution Four daughters and three sons.
No.20	What seven-letter word has hundreds of letters in it?	Solution Mailbox
No.21	If you had a ton of feathers and a ton of stones which would be heavier?	Solution Neither. They both weigh a ton.
No.22	Tom's mother has three children. One is named April, one is named May. What is the third one named?	Solution Tom
No.23	Two women apply for a job. They are identical. They have the same mother, father and birthday. The interviewer asks, "Are you twins?" to which they honestly reply, "No". How is this possible?	Solution Because they were triplets.
No.24	You are standing outside a closed door. On the other side of the door is a room that has three light bulbs in it. The room is completely sealed off from the outside. It has no windows and nothing can get in or out except through the door. On the outside of the room there are three light switches that control each of the respective light bulbs on the other side of the door. Your assignment is to determine which light switch controls which light bulb. You are allowed to enter the room only once, and once you come out, you must be able to state with 100% certainty which light switch controls which light bulb.	Solution Turn one light switch on, wait a few minutes, then turn it off and turn another light switch on. Go into the room and feel the light bulbs. The one that's still warm is connected to the switch that you first turned on, the one that is on was the second switch you turned on, and the last bulb is controlled by the switch that you didn't touch.
No.25	If a bottle and a cork cost a dollar and a nickel, and the bottle costs a dollar more than the cork, how much does the cork cost?	Solution Most people guess 5¢, but $1 more than 5¢ is $1.05, and if the bottle cost $1.05, the bottle and the cork would be $1.10, not $1.05. The cork actually costs 2½¢ and the bottle costs a dollar more, or $1 and 2½¢, making the total $1.05.