A toss of a 20-sided die is equally likely to be any integer between 1 and 20 inclusive. What is the expected value of the number tossed?

Answer: 10,5

Expected value is the sum of all possible value multiplied by the probability. The dice has 20 side which has an equal chance. So, the probability of each dice would be: 1/20 = 5%

The expected value would be:

1*5% + 2*5% ... + 20*5%=

(20+1) * 20/2 * 5% = 10.5