4.3 Using the calculator statistics mode

Bamboo is a fast-growing, strong grass useful for green building practices. A small research study explored the properties of bamboo when used as flooring material, including the bending strength (the Modulus of Rupture, or MOR, in MPa).

Five different bamboo floorboards were provided by Bamboo Flooring Australia Pty Ltd and assessed by the Queensland Department of Primary Industries (Gerber 2004).

The five MOR test results (in MPa) are shown in Table 4.1.

TABLE 4.1: The MOR (in MPa) for five bamboo boards
99.2 111.2 97.6 101.1 104
  1. Identify the type of RQ being answered: descriptive, relational, or interventional. Justify your answer.
  2. Use your calculator's statistics mode to compute the mean and the standard deviation.

Most calculators have two buttons that compute the standard deviation: one if the data are a sample, and one if the data are a population.

In practice, data are almost never a population.

If you are using your calculator correctly, you should get \(\bar{x}=102.62\) and \(s=5.356\). If you get \(s=4.790157\) for the standard deviation, you are using your calculator incorrectly, so please ask for help. You are probably pressing the incorrect button to get the standard deviation.
  1. Compute the median MOR of the flooring. (Most calculators cannot compute the median; you will need to do this by hand.)
  2. Compute the range of the MOR values.
  3. What specifications would you report about the MOR of bamboo flooring based on these data?
  4. What would be the implication if all five values were from the same floorboard?

References

Gerber S. Material properties of bamboo flooring. Indooroopilly, Queensland: Queensland Department of Primary Industries, for Bamboo Flooring Pty Ltd; 2004. Report No.: 2-04.