EXPECTATION, in the doctrine of chances, is applied to any contingent event, and is capable of being reduced to the rules of computation. Thus a sum of money in expectation when a particular event happens, has a determinate value before that event happens; so that if a person is to receive any sum, e. gr. 100. when an event takes place which has an equal probability of happening and failing, the value of the expectation is half that sum or 50.; and in all cases the expectation of obtaining any sum is estimated by multiplying the value of the sum expected by the fraction which represents the probability of obtaining it. The expectation of a person who has three chances in five of obtaining 100. is equal to or 60. and the
probability of obtaining 100. in this case is equal Expectation to .