Marketing companies are turning to mobile media for new opportunities. A recent study by IBM showed that 46% of all marketers conduct transactions on mobile websites. Suppose a random sample of 300 marketing companies is taken.

a. What is the probability that between 114 and 153 (inclusive) marketing companies are using a mobile website?

b. What is the probability that 51% or more of marketing companies are using a mobile website?

c. Suppose a random sample of 800 marketing companies is taken. Now what is the probability that 51% or more are using a mobile website? How does this answer differ from the answer in part (b)? Why do the answers differ?