The small mail-order firm Sea's Beginning has one phone line. An average of 60 people per hour call in orders, and it takes an average of one minute to handle a call. Time between calls and time to handle calls are exponentially distributed. If the phone line is busy, Sea's Beginning can put up to c - 1 people on hold. If c - 1 people are on hold, a caller gets a busy signal and calls a competitor. Sea's Beginning wants only 1% of all callers to get a busy signal. How many people should it be able to put on hold, that is, what is the required value of c?