A cellphone provider has the business objective of wanting to estimate the proportion subscribers who would upgrade to a new cellphone 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 cellphone at a reduced cost. Construct a 95% confidence interval estimate for the population proportion of subscribers that would upgrade to a new cellphone at a reduced cost. Is there sufficient evidence to infer that the business objective is true? Use a=0.05 Add other ones about the confidence intervals in this case