Tiled Pool

A rectangular cuboidal (aka right rectangular prism) pool with has the bottom and walls completely covered with equal sized square tiles. The bottom of the pool has 231 tiles and the four walls together have a total of 1024 tiles. How many tiles line the depth of this pool?


The answer is 16.

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3 solutions

Abhik Paul
May 25, 2014

Let the square tile have side 'x'. Also let the rectangular pool has length 'l', breadth 'b' and depth 'h'. Thus from the given statement we get two equations,

l b=231 { x }^{ 2 }

2 h (l+b)=1024*{ x }^{ 2 }

the first equations gives factors as 3,7,11. Thus three possible solutions are there: (33,7), (77,3) and (21,11). (21,11) is viable as (l+b) can't be a multiple of 10, from the latter equation.

Thus we get, h=16x. Hence number of tiles in line is 16.

did it the same way!

Gunjas Singh - 7 years ago
Reeshabh Ranjan
Jun 15, 2014

Take the square tiles for unit of measurement. The area of the base of the pool is 231 units. Now prime factorise 231, 231 = 3 11 7 Now, there are three cases of l*b:-

3*77..................case 1

21*11................case 2

33*7...................case 3

Now, we individually look at the perimeter made by all the cases.

In case 1, p = 160

In case 2, p = 64

In case 3, p = 80

Now, the area of 4 walls = perimeter * height = 1024. If we apply some logic, if p*h = 1024, h can't be in decimals [given in question]. So, for p=160 and p= 80, value of h doesn't fits the question. So, only for p = 64, values of h, i.e 1024/64 = 16 fits in the question's conditions. Hence, height, that is the number of tiles that line the depth of the pool is 16 units or 16 tiles.

Abdul Ashraf Ali
May 25, 2014

By trial and error method. The possible solutions for no. of tiles along length and breath were (3,77), (7,33) & (11,21). The no. of tiles along the height = 16.

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