Latest TCS Aptitude Question SOLUTION: Ramu our intrepid traveler goes to Egypt and is dazzled by its sphinxes and pyramids. At one such pyramid in Giza, he reads the inscription, "This pyramid was originally 28 levels

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Ramu our intrepid traveler goes to Egypt and is dazzled by its sphinxes and pyramids. At one such pyramid in Giza, he reads the inscription, "This pyramid was originally 28 levels tall with 4 faces". The pyramids are constructed by cubical blocks of rocks such that, on any face, the number of rocks at each level is one less than the level below it. He counts the number of rocks on one of the faces to be 10.0. Can you help Ramu find out how many levels have been lost over the last 4000 years due to the ravages of time?

Asked In TCS mohanapriya selvam (6 years ago)

Unsolved Read Solution (4)

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Read Solution (4) :

Prabhjot Singh Chhabra  (6 years ago)

(Assuming that the number of rocks counted on a face to be "100" instead of "10.0")

The pyramid is constructed originally with the top most level with 1 cubical rock. Thus the level below it will have 2 rocks at each face. it follows as 1,2,3,.... till the bottom most level which will have 28 rocks on a face(as there were 28 levels).

As now the upper levels are lost, we start from bottom most level which has 28 rocks.
28+27+26+ 19 (incomplete 4th level) = 100 rocks on a face.
Thus we can say that top 24 levels have been lost and 4th level(from bottom) is also incomplete.

Is this solution Helpfull? Yes (8) | No (2)  

BURLA SUMALATHA  (6 years ago)

it is 26 levels have been lost and 27 th level is partially lost.

Is this solution Helpfull? Yes (2) | No (2)  

Vartika Gupta  (6 years ago)

Sorry n=4 after solving
n/2(2a+(n-1)d)=10
So levels lost 28-4=24 levels lost

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Vartika Gupta  (6 years ago)

Let n levels are left. So by forming AP series we have
n,(n-1),(n-2),(n-3).......
Given no. Of rocks count to be 10
So by AP series sum formula
n/2(2a+(n-1)d)
Here a=1 because top level must have only one rock, and d=1(given level rock differ by one) so solving this n=5
These are the levels left so levels lost are 28-5=23 .

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