Question

The world's population is over 6 billion people. A estimate of 1/6 of them celebrate Christmas. Santa works from midnight until 6:00am. How much time does Santa have to visit each house? How many houses must he visit each second? Allow for 4 people per household and 24 time zones.
drwls
By going from east to west, Santa gets to cross time zone boundaries and set his watch back one hour 24 times. Therefore he has 24+6 = 30 hours of real elapsed time to accomplish his mission. To visit 1 billion Christmas-observing people in 30 hours, thatr means 10^9/(30*60*60) = 9260 people (2315 houses) per second.