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Finding the Fourth Proportional to 387.91, 581.78 and 137.78

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Solution

The fourth proportional to 387.91, 581.78 and 137.78 is: 206.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    387.91 : 581.78 = 137.78 : x
  2. Step 2: Convert to fraction form
    387.91/581.78 = 137.78/x
  3. Step 3: Cross multiply
    387.91x = 581.78 × 137.78
  4. Step 4: Simplify right side
    387.91x = 80,156.96
  5. Step 5: Solve for x
    x = 80,156.96/387.91
  6. Step 6: Final answer
    x = 206.64

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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.