Number 1 A guy who likes watching trains enjoys walking to a nearby railroad track to wait for a train to go by. Every time, upon his return, he makes a note of whether the one he saw was a passenger train or a freight train. Over the years, his figures show that 90 per cent of the trains have been passenger trains. One day he meets an official of the railroad and is surprised to learn that in fact passenger trains and feight trains are precisely equal in number. Why did the man, whom we may presume to have made random trips to the railroad tracks, see such a disproportionate number of passenger trains? Number 2 Bob owns a couple of hour glasses-- One is a four minute hourglass and the other is a seven minute hour glass. If Bob wants to measure 9 minutes, how could he do it?