Dallas-based Southwest Airlines is a discount airline that flies many popular routes across the US and several other countries. In order to compete with other airlines yet maintain profitability they attempt to fly their planes at capacity but they do allow customers to change their flights without a change fee. On average 17 customers (with a standard deviation of 10) cancel or are no shows for a typical flight. The average revenue collected from a flight is $145/seat. However, if the flight is overbooked and the airline needs to rebook a ticketed passenger, Southwest typically gives the customer an airline credit valued at $330 to use for a future flight. How many seats should Southwest Airlines overbook per flight