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Finding the Fourth Proportional to 420.40, 580.20 and 406.96

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Solution

The fourth proportional to 420.40, 580.20 and 406.96 is: 561.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.40 : 580.20 = 406.96 : x
  2. Step 2: Convert to fraction form
    420.40/580.20 = 406.96/x
  3. Step 3: Cross multiply
    420.40x = 580.20 × 406.96
  4. Step 4: Simplify right side
    420.40x = 236,118.19
  5. Step 5: Solve for x
    x = 236,118.19/420.40
  6. Step 6: Final answer
    x = 561.65

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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.