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Finding the Fourth Proportional to 815.14, 1,221.62 and 381.38

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Solution

The fourth proportional to 815.14, 1,221.62 and 381.38 is: 571.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    815.14 : 1,221.62 = 381.38 : x
  2. Step 2: Convert to fraction form
    815.14/1,221.62 = 381.38/x
  3. Step 3: Cross multiply
    815.14x = 1,221.62 × 381.38
  4. Step 4: Simplify right side
    815.14x = 465,901.44
  5. Step 5: Solve for x
    x = 465,901.44/815.14
  6. Step 6: Final answer
    x = 571.56

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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.