A) False. A sample statistic could equal to the population parameter. It won't always happen, but it might happen sometimes (in rare cases).
B) False. Point estimates are only defined for populations. They estimate a population parameter. For example, the sample mean xbar is a point estimate of the population mean (mu).
C) False. In practice, we will hardly know anything about the population. This includes the population size. The goal of statistics is to measure population parameters by using sample statistics as estimation methods.
D) True. We can easily calculate the sample size because it is relatively much smaller compared to the population. Plus, when selecting the sample, the sample size is often pre-determined to some set number. The sample size will help us determine things like the sample mean and the sample proportion.
