IIRC the certification of large planes by the FAA still uses the 1950's era value of 155 pounds average summer value per pax. I hope airlines today use a more realistic value for their weight and balance calculations. Some newer planes have load cells on the gear, they know the weight of the plane, fuel and cargo, so the average weight of men/women/children/bags/carry on and checked kitchen sinks is determined many times daily. I would really like some airline insider to let us know the number.

In todays world, I would guess a winter value of 200 average per pax plus 10 pounds of coat plus fifty pounds of carry on laptop/electronics/battery chargers plus 50 pounds of checked bags for a 310 pound average or twice the FAA certification value.