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Finding the Fourth Proportional to 431.41, 647.09 and 138.90

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Solution

The fourth proportional to 431.41, 647.09 and 138.90 is: 208.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    431.41 : 647.09 = 138.90 : x
  2. Step 2: Convert to fraction form
    431.41/647.09 = 138.90/x
  3. Step 3: Cross multiply
    431.41x = 647.09 × 138.90
  4. Step 4: Simplify right side
    431.41x = 89,880.80
  5. Step 5: Solve for x
    x = 89,880.80/431.41
  6. Step 6: Final answer
    x = 208.34

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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.