Jump to content
BrainDen.com - Brain Teasers

BMAD

Members
  • Content count

    2119
  • Joined

  • Last visited

  • Days Won

    71

Everything posted by BMAD

  1. Bill sold his motor scooter to Tom for $100. After driving it around for a few days Tom discovered it was in such a broken-down condition that he sold it back to Bill for $80. The next day Bill sold it to Herman for $90. What is Bill's total profit?
  2. The halfway glass

    You are in an empty room with a glass of water. The glass is a right cylinder that looks like it is about half-full, but you are unsure. What is the most accurate way, without spilling any water, to determine whether the glass is half-full, more than half-full, or less than half-full?
  3. The halfway glass

    I know what you mean but I don't think it is worded it right
  4. You and two of your friends would like to know the average of all of your salaries. You are each self-conscious about the amount of money you make and will not tell one another your salaries. What can you do to figure out the average salary?
  5. Bronx vs brooklyn

    A man lives in Manhattan near a subway express station. He has two girlfriends, one in Brooklyn, one in the Bronx. To visit either girl he must take a train. To go to the one in Brooklyn, he takes a train on the downtown side of the platform, and to visit the one in the Bronx, he takes a train on the uptown side of the same platform. Since he likes both girls equally well, he simply takes the first train that comes along. In this way he lets chance determine whether he rides to the Bronx or to Brooklyn. The young man reaches the subway platform at a random moment each Saturday afternoon. Brooklyn and Bronx trains arrive at the station equally often--every ten minutes. Yet for some obscure reason, he finds himself spending most of his time with the girl in Brooklyn. In fact, on average, he goes there nine times out of ten. Why are the odds so heavily in favor of Brooklyn?
  6. Russian Roulette

    You and four friends are playing Russian roulette, one bullet is in a chamber of a six chamber gun. Each of you must take a shot from the gun. The chamber will only be spun once, before anyone has taken a shot. If you got to chose, which position, 1st, 2nd, 3rd, 4th, or 5th would best help your chances of survival?
  7. Segment a segment

    In front of you is a line and a line segment. You need to dissect the line segment into 6 equal segments. Unfortunately you only possess two skills. you have the ability to mark points and you have the ability to draw straight segments. How will you segment the segment into six equal parts?
  8. Segment a segment

    There is a solution. the problem can be solved by them either being parallel or not intersecting. Since this is proving challenging, lets just focus on the parallel situation for now. Maybe I will repost the question for not intersecting later.
  9. A game token costs $10 to play. The pay out is $100. You can purchase multiple entries if you desire. For each entry you purchase, you must pick the lowest positive number that no one else picks. If there are ten people, including yourself, seeking to purchase tokens, what is your strategy?
  10. Who can go the lowest?

    yes, i meant integer
  11. Raven's Progressive Matrices

    Can you post an example?
  12. How many points would you need to have to uniquely determine an ellipse given that you know a foci is located at (0,0).
  13. Prove that x^(1/x) = x^-x has only one solution
  14. A rational solution

    For 0<x<y find an integer solution for x^y = y^x
  15. A rational solution

    is there another?
  16. Persistence

    A number's persistence is the number of steps required to reduce it to a single digit by multiplying all its digits to obtain a second number, then multiplying all the digits of that number to obtain a third number, and so on until a one-digit number is obtained. For example, 77 has a persistence of four because it requires four steps to reduce it to one digit: 77-49-36-18-8. The smallest number of persistence one is 10, the smallest of persistence two is 25, the smallest of persistence three is 39, and the smaller of persistence four is 77. What is the smallest number of persistence five?
  17. Month Codes

    Here is a list of months and a code for each January: 7110 February: 826 March: 5313 April: 541 May: 3513 June: 4610 July: 4710 What is the code for the month of August?
  18. Suppose superman can survive the vacuum of space (the comics are inconsistent with this ability). Let's say he is in the front of a spaceship that just crossed, what I believe in English is called, the event horizon for a black hole. That point where matter gets sucked into hole. Is it possible for superman to move to the rear of the ship and escape the black hole, assuming that the back of the ship hasn't crossed the event horizon?
  19. Finding a function

    Find a continuous function where the following identity is true: f(2x) = 3f(x)
  20. Abraham is tasked with reviewing damaged planes coming back from sorties over Germany in the Second World War. He has to review the damage of the planes to see which areas must be protected even more. Abraham finds that the fuselage and fuel system of returned planes are much more likely to be damaged by bullets or flak than the engines. What should he recommend to his superiors?
  21. A gambling problem

    A gambler has $5,000 and is playing a game of chance with a win probability of .95. Every time he wins, he raises his stake to 1/4, of his bankroll. The gambler doesn't reduce his stake when he loses If he keeps at it, what are his expected winnings?
  22. City Growth

    A town's population of size x doubled after 30 years (2x). How long ago was this population 1/2x?
  23. City Growth

    I intended your interpretation but came up with a much different answer than the ones reported forgive my lack of parenthesis what I meant for the problem is 1/(2x)
  24. A gambling problem

    His initial bet is $1250. Every time he wins, he calculates his total and takes 1/4 of it to bet. So initially he has 5000, 5000 x .25 = 1250. If he were to win, he would earn double his bet so he would have $6250. Recalculating he would bet $1562.50. If he loses his bet he would maintain that amount in his next bet. He keeps at it until he is unable to make his desired bet.
×