77% chance Palin could be Prez, if McCain elected? What do you think of my logic here:?

Consider the chance of an elected prez finishing their term. Of the 33 men elected up to Nixon - last not finishing - 7 didn't finish. (LIncoln, McKinley, JFK asinated; Taylor, FDR, Harrison died natural deaths; Nixon impeached) The chance of any prez finishing is therefore 26/33, or 78%. Since Nixon, we've been extraordinary lucky, because the chance of 4 prez's in a row finishing is 78% to the 5th power, or 30%. The chance of 1 more finishing is 78% to the 6th power, or 23%...Leaving 77% chance Palin could succeed (if elected) McCain.