A bank estimates that their average balance on demand deposit accounts is $2,000, net of float. Each account costs the bank $150 per year in processing costs. The bank collects an average of $7.50 per month on each account in service charges. Assume reserve requirements are 10%. What is the net cost of an average demand deposit? 3.0% 3.3% 3.6% 3.9% 4.2%