ujjagrawal

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About ujjagrawal

  • Rank
    Junior Member
  • Birthday 03/10/84

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  • Gender Male
  • Location India

ujjagrawal's Activity

  1. ujjagrawal added a post in a topic Crunching Gears   

  2. ujjagrawal added a post in a topic Who teaches so loudly??   

    How this answer is absolutely correct... ??? Your clue 2 says... The four teachers are: Lalita, a teacher who teaches in classroom A2
    As per above answer... A2 has Sushma... Are you sure of your puzzle... I think its all messed up...
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  3. ujjagrawal added a post in a topic An Uncertain Meeting   


    My workings

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  4. ujjagrawal added a post in a topic An Uncertain Meeting   

    I had got the same answers as you... but would like to see how you had worked it out...
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  5. ujjagrawal added a topic in New Logic/Math Puzzles   

    An Uncertain Meeting
    There are two friends, who decide to meet at a place between 5 PM to 6 PM everyday. What are the chances that, on a given day, they will be able to meet. Provided-


    Case 1: They agreed whoever comes first, will wait for 15 minutes for another friend to arrive.
    Case 2: One friend wait for 10 minutes and other for 20 minutes for another friend to arrive.

    And which of the above two cases holds better chances of there meeting ?
    • 7 replies
    • 1502 views
  6. ujjagrawal added a post in a topic Elevators problem   


    Thanks for raising above concerns... I assume, I framed the problem in bit hurry... here are the clarification to your concerns...

    AIM is to minimize average waiting time...

    Further assume, it's a residential building... all residents mostly travel between their floor and ground floor, so please ignore other in-between floor travels...

    Hope this problem make more sense now...
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  7. ujjagrawal added a post in a topic Elevators problem   

  8. ujjagrawal added a topic in New Logic/Math Puzzles   

    Elevators problem
    Most of the people, I understand, must not be happy with the logic by which the elevators on their building works. This is an opportunity for you to work on a logic that should be efficient, fair and a practical one.

    There is a 12 floors building (excluding ground level) with 2 elevators. Can you work out what should be the ideal position for the two elevators (in terms of floor numbers), while they are not in use i.e. idle. Assume equal probability of getting calls from all 12 floors.
    • 11 replies
    • 2217 views
  9. ujjagrawal added a post in a topic An unfair coin   

    Both of you are absolutely correct... Witzar I liked the way with ease you worked it out...
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  10. ujjagrawal added a topic in New Logic/Math Puzzles   

    An unfair coin
    An unfair coin has the property that when flipped four times, it has the same probability of turning up 2 heads and 2 tails (in any order) as 3 heads and 1 tail (in any order). What is the probability of getting a head in any one flip?
    • 3 replies
    • 808 views
  11. ujjagrawal added a topic in New Logic/Math Puzzles   

    A merciless emperor
    There's a merciless emperor who has 500 bottles of very expensive wine in his cellar.

    An assassin infiltrates the wine cellar to poison the wine. Fortunately the emperor’s guards catch the plotter after she has poisoned only one bottle. Unfortunately, the guards don’t know which one of the bottles is poisoned.

    The poison exhibits no symptoms until death. Death occurs within ten to twenty hours after consuming even the minutest amount of poison.

    The emperor decides he will get some of the prisoners in his dungeons to test the wine as he has handful of them about to be executed.

    What is the smallest number of prisoners that must have to drink from the bottles to be absolutely sure to find the poisoned bottle within 24 hours?
    • 12 replies
    • 1980 views
  12. ujjagrawal added a post in a topic Darts at Morty's   

    When Davey and Ian playing together:

    Combined probability of hitting a bull's eye will be -

    90% + 10% x 80% = 98% (If Davey fails to hit, when going first)
    or
    80% + 20% x 90% = 98% (If Ian fails to hit, when going first)

    Clearly, more than 97% probability by Alex, so Alex definitely made a BAD bet.
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  13. ujjagrawal added a post in a topic Classic eggs problem   

  14. ujjagrawal added a topic in New Logic/Math Puzzles   

    Classic eggs problem
    You have been given three eggs and your job is to figure out how high an egg can fall from a 120 story building before it breaks. The eggs might break from the first floor, or might even survive a drop from the 120th floor, you have no prior information about it. Except all three eggs are know to be of exactly same strength.

    What's the most efficient way to drop the eggs i.e. reducing the number of times you need to drop eggs and still able to determine the answer? You are allowed to break all three eggs, as long as you identify the correct floor afterwards.

    After you've solved the above problem, generalize. Define the "break floor" as the lowest floor in a building from which an egg would break if dropped. given an n story building and a supply of m eggs, find the strategy which minimizes (in the worst case) the number of experimental drops required to determine the break floor.
    • 6 replies
    • 2726 views