Using Excel functions to solve - For a marketing proposal for a mattress company, Lola is assigned the task of finding the average number of hours U.S. citizens sleep each night. Her results must be at the 99% level of confidence with a maximum margin of error of 0.25 hour. Assuming the standard deviation is 1.8 hours (based on a previous, reliable study), how many U.S. citizens must Lola survey?