Final answer:
The duration of suspension for underage alcohol purchase attempts varies by state but is influenced by the National Minimum Drinking Age Act of 1984's mandate to raise the drinking age to 21.
Step-by-step explanation:
The specific duration of the suspension for buying or attempting to buy alcoholic beverages by a person under 21 can vary by state, as each state has the authority to regulate alcohol laws under the Twenty-First Amendment. However, it's important to note that the National Minimum Drinking Age Act of 1984 implemented a federal mandate requiring states to raise their drinking age to 21 or face a reduction in federal highway funds. While this act does not set a uniform suspension period, states may choose to impose their own penalties for underage alcohol purchase attempts, which can include varying days of suspension of driving privileges among other legal consequences.