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Finding the Third Proportional to 319.78 and 649.69

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Solution

The third proportional to 319.78 and 649.69 is: 1,319.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    319.78 : 649.69 = 649.69 : x
  2. Step 2: Convert to fraction form
    319.78/649.69 = 649.69/x
  3. Step 3: Cross multiply
    319.78x = 649.69 × 649.69
  4. Step 4: Simplify right side
    319.78x = 422,093.85
  5. Step 5: Solve for x
    x = 422,093.85/319.78
  6. Step 6: Final answer
    x = 1,319.95

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Why These Related Problems?

These problems maintain the same ratio (2.03) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.