Consider Atlanta commute times for a random sample of 500 Atlanta commuters. We will assume that this sample is representative of the whole population, so that the whole population is essentially just copies of these 500 people.

The sample consists of times from Atlanta commuters. What is the parameter we would like to investigate and what is the correct notation for this parameter?

The parameter is the measure that represents the whole population. The most  common parameters are the mean and the proportion, the population mean is represented with the letter  μ  and the population proportion is represented with the letter  p. As the type pf variable is continuous (  times from Atlanta commuters) the parameter should be:

μ : Mean time of all Atlanta commuters