Jump to content
BrainDen.com - Brain Teasers


  • Content Count

  • Joined

  • Last visited

  • Days Won


Posts posted by DeGe

  1. DeGe's solution shows that {Mike and the North girl}

    can be interchanged with {Paul and the Fisher youngster},

    whose wrong answers can be either {7 0} and {3 4}

    or v.v, respectively.

    From what I remember while solving it, there were no unresolved elements and each piece fitted in one place only (I have now deleted the file that I used to work this out).

    The interchangeability between Mike/North and Paul/Fisher is also resolved. I don't remember how exactly I resolved it but it had something to do with there being only 3 girls names... Grace, Karen, and Dot. In case of interchanging Paul/Fisher and Mike/North, some other condition was being violated.

  2. Ask the server for time. Let us say you sent the request at time T; this request reaches the server at time T+t1. The server sends the time T+t1.
    So, you get the time T+t1, but the actual time now is T+t1+t2 when you get the time.

    Program such that you send another request at the very instant you get the first response from the server.

    So, at time T+t1+t2, you send the second request, and the time you receive from the server is T+2t1+t2 while the actual time is T+2t1+2t2 when you get this time.

    Calculate the difference between the two times recieved. You now know how much is t1+t2.

    Now, ask the server to send to send you the time (Tn) exactly n seconds later; for example you ask the server what time will it be after 30 seconds.

    As before, you will get the time Tn+t1, when the actual time is Tn+t1+t2.

    Subtract t1+t2 from the time Tn+t1 received from the server and set your computer clock to Tn after n seconds.

  3. The problem statement says

    • "His truck can only hold 1000 apples."

    ‚Äčthe update says that the store is 1000 miles away

    If the driver starts with a full load [1000 apples] and drives 1000 miles, he will have 0 apples left upon arrival.

    Thus, unless he can ferry apples to some point(s) in between and then move these forward, there is no way to every deliver even 1 apple.

    If we assume that there is a point halfway [500 miles] then he could do the following:

    • leave the warehouse with 1000 apples
    • drive 500 miles [now has 500 apples]
    • leave the apples at the halfway point [now has 500 apples]
    • drive back to the ware house
    • leave the warehouse with 1000 apples
    • drive 500 miles [now has 500 apples]
    • Picks up 500 the apples at the halfway point [now has 1000 apples in the truck and 0 apples at the halfway point]]
    • Drives the remaining 500 miles to the store and delivers 500 apples

    Thus for 2 trips[500 and 1000 miles one way (3000 miles total round trip)] 500 apples can be delivered

    to deliver 3000 apples would require:

    • an interim storage area at 500 miles
    • 6 "short" round trips between the warehouse and the interim storage area [1000 miles R/T each]
    • 6 "long" round trips from the warehouse [stopping at the interim storage area to reload] to the store [2000 miles R/T each]


    • you can break this up many ways
    • it is not clear what the optimal interim storage area distance [from the ware house] is [and if more than 1 helps]

    Yes, but for returning also he would need to eat apples

    So, if he goes 500KM, he would eat 500 while going and 500 while coming back.


  4. Each digit repeats itself in each position as follows:

    in ones position 1000 times

    in tens position 100 times

    in hundreds position 10 times

    in 1000 position 1 times

    and 1 appears once in 10 000

    Now, 0 + 1 + 2 +3 .... + 9 = 45

    So, sum of digits is 45*1000 + 45*100 + 45*10 + 45*1 + 1 = 45*1111 + 1 = 49996

  • Create New...