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Finding the Fourth Proportional to 813.88, 1,221.08 and 381.40

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Solution

The fourth proportional to 813.88, 1,221.08 and 381.40 is: 572.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    813.88 : 1,221.08 = 381.40 : x
  2. Step 2: Convert to fraction form
    813.88/1,221.08 = 381.40/x
  3. Step 3: Cross multiply
    813.88x = 1,221.08 × 381.40
  4. Step 4: Simplify right side
    813.88x = 465,719.91
  5. Step 5: Solve for x
    x = 465,719.91/813.88
  6. Step 6: Final answer
    x = 572.22

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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.