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Finding the Fourth Proportional to 515.78, 711.78 and 308.78

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Solution

The fourth proportional to 515.78, 711.78 and 308.78 is: 426.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    515.78 : 711.78 = 308.78 : x
  2. Step 2: Convert to fraction form
    515.78/711.78 = 308.78/x
  3. Step 3: Cross multiply
    515.78x = 711.78 × 308.78
  4. Step 4: Simplify right side
    515.78x = 219,783.43
  5. Step 5: Solve for x
    x = 219,783.43/515.78
  6. Step 6: Final answer
    x = 426.12

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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.