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Finding the Fourth Proportional to 431.20, 644.82 and 409

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Solution

The fourth proportional to 431.20, 644.82 and 409 is: 611.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    431.20 : 644.82 = 409 : x
  2. Step 2: Convert to fraction form
    431.20/644.82 = 409/x
  3. Step 3: Cross multiply
    431.20x = 644.82 × 409
  4. Step 4: Simplify right side
    431.20x = 263,731.38
  5. Step 5: Solve for x
    x = 263,731.38/431.20
  6. Step 6: Final answer
    x = 611.62

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.