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Finding the Fourth Proportional to 420.34, 580.79 and 405.56

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Solution

The fourth proportional to 420.34, 580.79 and 405.56 is: 560.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.34 : 580.79 = 405.56 : x
  2. Step 2: Convert to fraction form
    420.34/580.79 = 405.56/x
  3. Step 3: Cross multiply
    420.34x = 580.79 × 405.56
  4. Step 4: Simplify right side
    420.34x = 235,540.26
  5. Step 5: Solve for x
    x = 235,540.26/420.34
  6. Step 6: Final answer
    x = 560.36

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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.