š Key Concepts
ā¢ Chart scale ratios always compare a distance on the chart to the SAME UNIT of distance on the Earth
ā¢ In a ratio like 1:5,000,000, the first number is the distance on the chart, the second is the distance on the Earth
ā¢ Remember that chart scales are usually defined in the same units (e.g., inches to inches, centimeters to centimeters)
š Think About
ā¢ Ask yourself: In a scale written as 1:5,000,000, what does the "1" represent and what does the "5,000,000" represent?
ā¢ Look carefully at which answers keep the same units on both sides of the ratio (for example, inches to inches). Which choices change units?
ā¢ If you measured 1 inch on the chart, what would that represent on the Earthās surface according to a 1:5,000,000 scale?
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Before You Answer
ā¢ Make sure the ratio compares same units to same units (e.g., inches to inches, cm to cm)
ā¢ Check whether the answer option is keeping the meaning: first number = chart distance, second number = Earth distance
ā¢ Eliminate any option that uses nautical miles in the ratio, because standard chart scales are not written that way