According to a 2018 Pew Research Center report on social media use, 28% of American adults use Instagram. Suppose a sample of 150 American adults is randomly selected. We are interested in finding the probability that the proportion of the sample who use Instagram is greater than 30%.

a. Without doing any calculations, determine whether this probability will be greater than 50% or less than 50%. Explain your reasoning.

b. Calculate the probability that the sample proportion is 30% or more.