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Finding the Fourth Proportional to 711.20, 1,067.90 and 387.20

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Solution

The fourth proportional to 711.20, 1,067.90 and 387.20 is: 581.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    711.20 : 1,067.90 = 387.20 : x
  2. Step 2: Convert to fraction form
    711.20/1,067.90 = 387.20/x
  3. Step 3: Cross multiply
    711.20x = 1,067.90 × 387.20
  4. Step 4: Simplify right side
    711.20x = 413,490.88
  5. Step 5: Solve for x
    x = 413,490.88/711.20
  6. Step 6: Final answer
    x = 581.40

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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.