🔍 Key Concepts

• Standard sea-level pressure and its common units in meteorology and navigation • How inches of mercury, millibars, and millimeters of mercury relate to each other • Remember that not all options are in the same type of unit (pressure vs. length of a water column)

💭 Think About

• Which of the answer choices are standard reference values you’ve seen before for mean sea-level pressure? • Are there any options that convert inches of mercury into a different fluid (water instead of mercury)? How does the density difference affect the equivalence? • Have you seen a typical weather map pressure value that corresponds to 29.92 inches of mercury?

✅ Before You Answer

• Identify which options use mercury vs. water as the fluid column—those are not directly interchangeable without considering density. • Recall the common meteorological standard: standard atmosphere at sea level in millibars (or hectopascals). • Double-check which numerical value you most often see associated with “standard pressure” in aviation, marine weather, and barometer settings.