The article “Write It by Hand to Make It Stick” (Advertising Age, July 27, 2016) summarizes data from a survey of 1001 students age 13 to 19. Of the students surveyed, 851 reported that they learn best using a mix of digital and nondigital tools. Construct and interpret a 95% confidence interval for the proportion of students age 13 to 19 who would say that they learn best using a mix of digital and non-digital tools. For the method used to construct the interval to be valid, what assumption about the sample must be reasonable?