Please answer this using formulas and not on excel Sally Gordon has just completed her MBA degree and is proud to have e

[answerhappygod]

Please answer this using formulas and not on excel
Sally Gordon has just completed her MBA degree and is proud tohave earned a promotion toVice President for Customer Services at the First Bank of Seattle.One of her responsibilities isto manage how tellers provide services to customers, so she istaking a hard look at this area ofthe bank’s operations. Customers needing teller service arriverandomly at a mean rate of 30 perhour. Customers wait in a single line and are served by the nextavailable teller when they reachthe front of the line. Each service takes a variable amount of time(assume an exponentialdistribution), but on average can be completed in 3 minutes. Thetellers earn an average wage of$18 per hour.
Please answer this using formulas
(a)
Company policy is to have no more than a 10% chance that acustomer will need to wait morethan 5 minutes before reaching a teller. How many tellers need tobe used in order to meet thisstandard?