Question

The ceramic tile used in the construction of the floors in a mall must be sturdy, easy to clean, and long-lasting. Before installing a specific type of tile, a construction firm orders a box of 25 of the proposed type of tile and uses a standard strength test on each tile in the box. The standard breaking test consists of someone putting each tile half way on a table in a specialized way and then placing standardized weights on the part of the tile that is not on the table until the tile breaks. The results are used to determine whether this type of tile will be used throughout the new mall.

a) Is this an observational or an experimental study? Please explain your answer.

b) What is the sample in this problem?
The 25 tiles of this type.
All tiles of this type.
25 tiles of any type of tiles used on floors in malls.
All tiles used on floors in malls.

c) Is this sample random? If so, justify your answer. If not, describe a possible technique that could be used to obtain a random sample.

Answer 1

a)

We are observing the strengths of tiles by performing standard strength test (giving treatments) and based on the results, we determine whether this type of tile will be used throughout the new mall . So, this is an experimental study.

b)

The sample in the problem is

The 25 tiles of this type.

c)

The sample is a box of 25 of the proposed type of tile. So, this is not a random sample as all the tiles comes from a same box which may have different strength than the tiles from other box. In a random sample, let we select 5 random samples of box and from those boxes, we randomly select 5 tiles.