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Finding the Fourth Proportional to 381.69, 572.40 and 138.20

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Solution

The fourth proportional to 381.69, 572.40 and 138.20 is: 207.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    381.69 : 572.40 = 138.20 : x
  2. Step 2: Convert to fraction form
    381.69/572.40 = 138.20/x
  3. Step 3: Cross multiply
    381.69x = 572.40 × 138.20
  4. Step 4: Simplify right side
    381.69x = 79,102.82
  5. Step 5: Solve for x
    x = 79,102.82/381.69
  6. Step 6: Final answer
    x = 207.24

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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.