Researchers compare the body composition of cattle feeding on a grain diet with that of cattle feeding on a grass diet. this method of gathering data is classified as a. a census. b. a sample survey. c. an experiment. d. an observational study.

Suppose that the price p, in dollars, and the number of sales, x, of a certain item follow the equation 4 p plus 4 x plus 2 pxequals56. suppose also that p and x are both functions of time, measured in days. find the rate at which x is changing when xequals2, pequals6, and startfraction dp over dt endfraction equals1.5.