A cell phone provider has the business objective of wanting to estimate the proportion of subscribers who would upgrade to a new cell phone with improved features if it were made available at a substantially reduced cost. Data are collected from a random sample of 500 subscribers. The results indicate that 135 of the subscribers would upgrade to a new cell phone at a reduced cost.
a. At the 0.05 level of significance, is there evidence that more than 20% of the customers would upgrade to a new cell phone at a reduced cost?
b. How would the manager in charge of promotional programs concerning residential customers use the results in (a)?