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Finding the Third Proportional to 391.78 and 857.06

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Solution

The third proportional to 391.78 and 857.06 is: 1,874.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    391.78 : 857.06 = 857.06 : x
  2. Step 2: Convert to fraction form
    391.78/857.06 = 857.06/x
  3. Step 3: Cross multiply
    391.78x = 857.06 × 857.06
  4. Step 4: Simplify right side
    391.78x = 734,556.13
  5. Step 5: Solve for x
    x = 734,556.13/391.78
  6. Step 6: Final answer
    x = 1,874.91

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Why These Related Problems?

These problems maintain the same ratio (2.19) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.