Should not the question be what is the probability that your coin is a silver dollar? Also the distinction between dollars and silver dollars is not clear. Your result implies dollars includes silver dollars.
I understood that 50% of the coins are dollars and of those 20% are silver, but it can be understood that 50% of the coins are dollars and 20% of the coins are silver dollars.
@Jig, actually it's 20% of the total. See added clarification.
2/5 should be a correct answer, but it shows as incorrect
The question asks you to enter the answer as an integer or decimal.