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Finding the Fourth Proportional to 421.13, 628.24 and 391.67

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Solution

The fourth proportional to 421.13, 628.24 and 391.67 is: 584.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.13 : 628.24 = 391.67 : x
  2. Step 2: Convert to fraction form
    421.13/628.24 = 391.67/x
  3. Step 3: Cross multiply
    421.13x = 628.24 × 391.67
  4. Step 4: Simplify right side
    421.13x = 246,062.76
  5. Step 5: Solve for x
    x = 246,062.76/421.13
  6. Step 6: Final answer
    x = 584.29

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.