Use this description for Questions 15 4. Dr. Voelz and his students are studying caddisfly larvae (Trichoptera) in the Mississippi River. Like many insects, caddisflies grow in a series of easily distinguishable stages (called instars), separated by a molt. He is Interested in understanding the distribution of growth stages in three families of caddisflies. For each insect captured, he identifies its family (one of the three) and its instar (first, second, third). 1. If Dr. Voelz wants to know how many first instar larvae have been found, this question requires us to calculate a a. Mean b. Conditional probability c. Count d Marginal value 2. The explanatory vanable in Question 1 above was a, Instar b Family of caddisfly c There are two response variables d. There is really only one variable in the question 3, If Dr. Voelz wants to estimate how many of the third instar larvae in the population are in the family Hydropsychidae, this question requires us to calculate a a Mean b. Conditional probability c Count d Marginal value The explanatory variable in the question above is a Instar D. Family of caddisfly c There are two response vanables d. There is really only one variable in the