The examples you give are for the rear axle (final drive), not the transmission. They are always written as a ratio of revolutions of the input gear (or shaft) compared to the number of revolutions of the output gear (or shaft). For consistency, it is almost universal that ONE revolution of the output gear is used.

So... a rear axle with a 3.73:1 gearset will require 3.73 turns of the drivehaft for one full turn of the rear wheels (on the ground so they turn as one unit). You could also say that for every 100 wheel revolutions, the driveshaft will turn 373 times. Substitute a four-eleven rear, and the driveshaft will turn 411 revolutions for the same 100 revolutions of the wheels. More torque multiplication, more noise, more fuel, less efficiency.