Final answer:
Given the information, we can only confirm that both men took a sip of water 72 minutes after starting the marathon. We cannot determine the second man's sip frequency without further details.
Step-by-step explanation:
The question involves finding out how often the second man took a sip of water if the first man took a sip every 9 minutes. The initial information provided doesn't include the frequency of the second man's water intake. However, since both men took their first sip at the same time—72 minutes after starting—there's an implication that the second man's drinking frequency must also fit into a schedule that aligns with the 72-minute mark. Without an additional specific time when the second man takes another sip, we cannot determine his drinking frequency exactly.
Therefore, the only fact we can state with certainty is that they both took a sip at the 72-minute mark. Any other assertion about the second man's drinking frequency would be speculative.