a) This is a simple random sample. This means that there is no bias affecting our estimate. In a simple random sample, every member of the population has an equal chance of being selected for the sample. This is not affected by bias.

b) This particular sample will be affected by variability. In other words, the make up of the population itself will affect our result. Because we are looking at the heights of people, we have to consider that there are both men and women in this sample. This is bimodal data. Bimodal data is difficult to describe with summary statistics, at least in any meaningful way. The fact that there are both men and women will affect our sample's variability.