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Finding the Fourth Proportional to 809.87, 1,214.46 and 399.20

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Solution

The fourth proportional to 809.87, 1,214.46 and 399.20 is: 598.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    809.87 : 1,214.46 = 399.20 : x
  2. Step 2: Convert to fraction form
    809.87/1,214.46 = 399.20/x
  3. Step 3: Cross multiply
    809.87x = 1,214.46 × 399.20
  4. Step 4: Simplify right side
    809.87x = 484,806.36
  5. Step 5: Solve for x
    x = 484,806.36/809.87
  6. Step 6: Final answer
    x = 598.63

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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.