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Finding the Fourth Proportional to 431.28, 646.71 and 138.69

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Solution

The fourth proportional to 431.28, 646.71 and 138.69 is: 207.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    431.28 : 646.71 = 138.69 : x
  2. Step 2: Convert to fraction form
    431.28/646.71 = 138.69/x
  3. Step 3: Cross multiply
    431.28x = 646.71 × 138.69
  4. Step 4: Simplify right side
    431.28x = 89,692.21
  5. Step 5: Solve for x
    x = 89,692.21/431.28
  6. Step 6: Final answer
    x = 207.97

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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.