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