The telephone company wants to investigate the desirability of beginning a marketing campaign that would offer customers the right to purchase an additional telephone line at a substantially reduced installation cost. The campaign will be initiated if there is evidence that more than 20% of the customers would consider purchasing an additional telephone line if it were made available at a substantially reduced installation cost. A random sample of 500 households is selected. The results indicate that 135 of the households would purchase the additional telephone line at a reduced installation cost.
a. At the 0.05 level of significance, is there evidence that more than 20% of the customers would purchase the additional telephone line?
b. How would the manager in charge of promotional programs concerning residential customers use the results in (a)?