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Finding the Fourth Proportional to 513.78, 708.40 and 420.30

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Solution

The fourth proportional to 513.78, 708.40 and 420.30 is: 579.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    513.78 : 708.40 = 420.30 : x
  2. Step 2: Convert to fraction form
    513.78/708.40 = 420.30/x
  3. Step 3: Cross multiply
    513.78x = 708.40 × 420.30
  4. Step 4: Simplify right side
    513.78x = 297,740.52
  5. Step 5: Solve for x
    x = 297,740.52/513.78
  6. Step 6: Final answer
    x = 579.51

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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.