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Finding the Fourth Proportional to 680.78, 939.12 and 515

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Solution

The fourth proportional to 680.78, 939.12 and 515 is: 710.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    680.78 : 939.12 = 515 : x
  2. Step 2: Convert to fraction form
    680.78/939.12 = 515/x
  3. Step 3: Cross multiply
    680.78x = 939.12 × 515
  4. Step 4: Simplify right side
    680.78x = 483,646.80
  5. Step 5: Solve for x
    x = 483,646.80/680.78
  6. Step 6: Final answer
    x = 710.43

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.