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Finding the Fourth Proportional to 813.38, 1,220.31 and 423.45

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Solution

The fourth proportional to 813.38, 1,220.31 and 423.45 is: 635.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    813.38 : 1,220.31 = 423.45 : x
  2. Step 2: Convert to fraction form
    813.38/1,220.31 = 423.45/x
  3. Step 3: Cross multiply
    813.38x = 1,220.31 × 423.45
  4. Step 4: Simplify right side
    813.38x = 516,740.27
  5. Step 5: Solve for x
    x = 516,740.27/813.38
  6. Step 6: Final answer
    x = 635.30

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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.