4. A researcher wants to determine the proportion of elm trees in Windsor, Ontario, dying of Dutch elm disease. Past experiments, based on large sample sizes, have shown this proportion to be 0.3. What sample size does the researcher need in order to estimate this proportion to Within 0.04 with 98% condence? 5. In a random sample of 519 students, it was found that 285 were introverts. a) Let 10 represent the proportion of all students who are introverts. Find a point estimate for p. b) Find a 90% condence interval for p