Acompany is marketing its newest product to a school of 30,000 students. the company relies on internet advertisements and word-of-mouth. the company estimates that every day a random sample of 1,000 students see an internet advertisement for their product; however, some of these students may have already been exposed to their product by internet or word-of-mouth. the company also estimates that every day, 10 percent of the students who have already been exposed to the product will tell a friend about the product. assume that these students always tell a friend who hasn't already heard about the product somewhere else. if p is the number of students who have been exposed to the product after an arbitrary time t (measured in days), set up a differential equation for p in terms of t. dp/dt =