Answer:
There will be 40 winners.
There is a 95% chance of not winning.
Step-by-step explanation:
In order to calculate the winners per draw, we just have to multiply the chance of winning by the entrants.
We have 800 entrants, and there is 1/20 chance of winning, so we just multiply it:

And now to calculate the percentage we just have to do a rule of thirds:
If 20 is 100% how much would 1 be?


So now we now that the percentage of winners would be 5%.