Assume a researcher wants to estimate the percent of Centennial College students who have cell phones. Five hundred randomly selected students are surveyed to determine whether they have cell phones. Of the 500 students surveyed, 481 responded yes - they own cell phones. Using a 99% confidence level, find:

a) The margin of error (or the error bound). Express your answer correct to 3 decimal points. [2 marks]

b) A confidence interval estimate for the true proportion of Centennial College students who have cell phones. Type the 2 interval limits starting with the lower one; separate the 2 values by a comma - no spaces. Express both answers correct to 3 decimal places. [2 marks]