A forced-choice design is often used to compare the attractiveness of pheromones to insects. A Y-tube is used. The pheromone is place on one branch; the control on the second branch; and the insect on the third branch. The insect then chooses one of the two branches. Suppose that28 of 70 insects choose the pheromone branch. The 95% confidence interval for the proportion of the population that prefers the pheromone branch is:

(Hint:(If n*p and n(1-p)>10, then use the Normal approximation, otherwise use the Exact method)