New York City is on eastern standard time, St. Louis is on central standard time (1 hour earlier than eastern standard time), and Las Vegas is on Pacific standard time (3 hours earlier than eastern standard time). A flight leaves New York City at 9 a.m.eastern standard time, stops for 50 min in St. Louis, and arrives in Las Vegas at 1:35 p.m.Pacific time. How long is the plane actually  flying?