One of your employees has suggested that your company develop a new product. A survey is designed to study whether or not there is interest in the new product. The response is on a 1 to 5 scale with 1 indicating definitely would not purchase, · · ·, and 5 indicating definitely would purchase. For an initial analysis, you will record the responses 1, 2, and 3 as No, and 4 and 5 as Yes.
a. 5 people are surveyed. What is the probability that at least 3 of them answered Yes?
b. 100 people are surveyed. What is the approximate probability that between 45% to 52% of people answered Yes?
For part a) There are 5 choices that people can respond by 1, 2 ,3 ,4 and 5. Since 1, 2 and 3 are considered "No", the probability of someone answering "No" is 3/5. For choices 4 and 4, the probability of someone responding with that is 2/5.
This looks like it fallows a binomial distribution so I calculated the probability of P(3) + P(4) + P(5).
However for part b), I'm confused. I can calculate the probability of someone saying yes but I don't know how to calculate the probability that a percentage of people saying yes. Does anyone know how to approach this question? I though about using the Z table, but that already calculates area.