Final answer:
The value of the constant c in a probability mass function can be any real number.
Step-by-step explanation:
To find the value of the constant c so that P(x) is a probability mass function, we need to ensure that the probability is equal to one. In a probability mass function, the sum of all probabilities must equal one. Since P(x = c) = 0 for any individual value, the value of c does not affect the sum. Therefore, the value of the constant c can be any real number.
Example:
If we have a probability mass function P(x) = 0.2 for x = 3 and P(x) = 0.8 for x = 7, the value of c does not affect the probabilities, and the constant c can be any real number.