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Problem Two: Pyramids By The Block

Nov 16th, 2006 by Allen

In a catalog, you read about a set of blocks. There are 1029 blocks; all are identical in volume. They can be assembled into several tiers which are 1 foot thick and stack to form a pyramid. (The pyramid has a square base; its four sides are equivalent isosceles triangles.) How tall is this pyramid?

Posted in Mathematical | 2 Comments

2 Responses to “Problem Two: Pyramids By The Block”

  1. on 19 Dec 2006 at 11:24 am   xysk

    14 ft?

  2. on 02 Feb 2007 at 11:06 pm   mathieu

    I am not sure why the number is 1029 and not 1015…
    Shouldn’t you solve:

    1 + 4 + 9 + … + i^2 + … + n^2 = 1015

    n * (n+1) * (2n+1) / 6 = 1015

    which lead to:
    n = 14

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