To ensure that Joe's sample of 10,000 adults is representative of the U.S. population and avoids bias, he should aim to select an equal number of participants from each of the 50 states.
To find out how many people he should choose from each state, you can divide the total sample size by the number of states:
\[ \text{Number of people from each state} = \frac{\text{Total sample size}}{\text{Number of states}} = \frac{10,000}{50} = 200 \]
Thus, Joe should choose 200 adults from each state.