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Finding the Fourth Proportional to 439.90, 661.20 and 431.80

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Solution

The fourth proportional to 439.90, 661.20 and 431.80 is: 649.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    439.90 : 661.20 = 431.80 : x
  2. Step 2: Convert to fraction form
    439.90/661.20 = 431.80/x
  3. Step 3: Cross multiply
    439.90x = 661.20 × 431.80
  4. Step 4: Simplify right side
    439.90x = 285,506.16
  5. Step 5: Solve for x
    x = 285,506.16/439.90
  6. Step 6: Final answer
    x = 649.03

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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.