Answer:
N is a population parameter; the estimate of N is a statistic.
Step-by-step explanation:
A measure of a population is called a parameter. The population is the entire set we are measuring. In this problem, N is the total number of warplanes fielded by the Germans. Since it is the total, it is a population, making it a parameter.
A measure of a sample is a statistic. This means an estimate of N based on a sample would be a statistic.