Final answer:
The maximum likelihood estimator (MLE) for the parameter M of a discrete uniform distribution, given the sample data, is the maximum value observed, which in this case would be 10.
Step-by-step explanation:
The question refers to the estimation of the parameter M in a discrete uniform distribution using the method of maximum likelihood estimation (MLE).
Given the sample data, we know that each value is drawn randomly from the set {1, 2, ..., 2M}, with a distribution limit of 21. Since the largest observed value in the sample is 20,
we can deduce that the parameter M must be at least 10.
Therefore, our MLE for M would be 10, as the MLE for a discrete uniform distribution is the maximum value observed in the sample.