4. [10%] An online poll states that 50% people dislike a certain policy. For the next poll on the same topic, let
be the point estimate of the true proportion
±2.5%? (Note:
is the cumulative distribution function of a standard normal random variable Z. And 1.962 = 3.8416, 1.642 =2.6896, 1.282 =1.6384.)