Half life is the period of time for a substance undergoing decay, to decrease by half. Also the name originally was used to describe a characteristic of unstable atoms.
http://answers.ask.com/Science/Other/how_to_calcul...

1. Find the finish time of either your last race or your last long training run. An alternative is to use the length of time you hope it will take to finish the half marathon. Most
http://www.ehow.com/how_8294631_calculatehalfmar...

1 Divide the amount of the substance at one point in time by the amount remaining after a period of time. The formula for calculating half life is as follows: t 1/2 = t * ln(2)/ln
http://www.wikihow.com/CalculateHalfLife

Volume of a cylinder is (to find half, divide by 2) V. cylinder. = A. base. * height. In a cylinder, the base is a circle and the area of a circle can be found: A. circle. = pi *
http://wiki.answers.com/Q/How_to_calculate_the_vol...
