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Finding the Fourth Proportional to 518.78, 715.83 and 311.78

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Solution

The fourth proportional to 518.78, 715.83 and 311.78 is: 430.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    518.78 : 715.83 = 311.78 : x
  2. Step 2: Convert to fraction form
    518.78/715.83 = 311.78/x
  3. Step 3: Cross multiply
    518.78x = 715.83 × 311.78
  4. Step 4: Simplify right side
    518.78x = 223,181.48
  5. Step 5: Solve for x
    x = 223,181.48/518.78
  6. Step 6: Final answer
    x = 430.20

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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.