The average of a set of numbers is simply the sum of the numbers divided by the total number of values in the set. For example, suppose we want the average of 24 , 55 , 17 , 87 and 100 . Simply get the sum of the numbers 24 + 55 + 17 + 87 + 100 = 283 and divide by 5 to get 56.6
For your example Tom it would be the total awarded prize money divided by the total number of prize winners: $160,554,599.39 / 49,141 = $3,267.22 per winner - average.