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Finding the Fourth Proportional to 813.20, 1,219.79 and 380.30

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Solution

The fourth proportional to 813.20, 1,219.79 and 380.30 is: 570.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    813.20 : 1,219.79 = 380.30 : x
  2. Step 2: Convert to fraction form
    813.20/1,219.79 = 380.30/x
  3. Step 3: Cross multiply
    813.20x = 1,219.79 × 380.30
  4. Step 4: Simplify right side
    813.20x = 463,880.99
  5. Step 5: Solve for x
    x = 463,880.99/813.20
  6. Step 6: Final answer
    x = 570.44

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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.