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Finding the Fourth Proportional to 431.57, 647.36 and 139.07

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Solution

The fourth proportional to 431.57, 647.36 and 139.07 is: 208.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    431.57 : 647.36 = 139.07 : x
  2. Step 2: Convert to fraction form
    431.57/647.36 = 139.07/x
  3. Step 3: Cross multiply
    431.57x = 647.36 × 139.07
  4. Step 4: Simplify right side
    431.57x = 90,029.80
  5. Step 5: Solve for x
    x = 90,029.80/431.57
  6. Step 6: Final answer
    x = 208.61

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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.