Final answer:
A typical value for marine salinity is 3.5%, which aligns with the average seawater composition of approximately 3.0% NaCl and 0.5% other salts.
Step-by-step explanation:
The percentage that represents a typical value for marine salinity is 3.5%. For example, a saline solution analogous to seawater with a mass of 355 g and 36.5 g of NaCl dissolved in it has a mass/mass percent concentration of approximately 10.28%, but this example is more concentrated than typical seawater. In reality, seawater salinity, as referenced in scientific literature and understood in marine biology, is on average about 3.5%. This is aligned with the data suggesting seawater has approximately 3.0% NaCl by mass with about 0.5% of other salts, giving us the typical salinity percentage.