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Finding the Fourth Proportional to 591.20, 815.40 and 391.67

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Solution

The fourth proportional to 591.20, 815.40 and 391.67 is: 540.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    591.20 : 815.40 = 391.67 : x
  2. Step 2: Convert to fraction form
    591.20/815.40 = 391.67/x
  3. Step 3: Cross multiply
    591.20x = 815.40 × 391.67
  4. Step 4: Simplify right side
    591.20x = 319,367.72
  5. Step 5: Solve for x
    x = 319,367.72/591.20
  6. Step 6: Final answer
    x = 540.21

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.