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Finding the Fourth Proportional to 814.20, 1,219.80 and 380.40

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Solution

The fourth proportional to 814.20, 1,219.80 and 380.40 is: 569.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    814.20 : 1,219.80 = 380.40 : x
  2. Step 2: Convert to fraction form
    814.20/1,219.80 = 380.40/x
  3. Step 3: Cross multiply
    814.20x = 1,219.80 × 380.40
  4. Step 4: Simplify right side
    814.20x = 464,011.92
  5. Step 5: Solve for x
    x = 464,011.92/814.20
  6. Step 6: Final answer
    x = 569.90

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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.