At a college there are 120 freshmen, 90 sophomores, 110 juniors, and 80 seniors. A school administrator selects a random sample of 12 of the freshmen, a random sample of 9 of the sophomores, a random sample of 11 of the juniors, and a random sample of 8 of the seniors. She then interviews all the students selected. Identify the type of sampling used in this example.

Stratified sampling

Step-by-step explanation:

The is a type of sampling in which the population of interest is divided into subpopulations and then each subpopulation is randomly sampled.

In this case study, instead of just doing a random sampling of all students, the research divided the population of all students into subpopulations which includes freshmen, sophomores, juniors and seniors and then she makes a random sampling of each of these subpopulations.

f(x) has value 150 at x= 0

and 0 at x= 3

so d(f(x))/dt = slope = -150/3 = -50