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Finding the Fourth Proportional to 809.91, 1,215.33 and 399.17

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Solution

The fourth proportional to 809.91, 1,215.33 and 399.17 is: 598.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    809.91 : 1,215.33 = 399.17 : x
  2. Step 2: Convert to fraction form
    809.91/1,215.33 = 399.17/x
  3. Step 3: Cross multiply
    809.91x = 1,215.33 × 399.17
  4. Step 4: Simplify right side
    809.91x = 485,117.20
  5. Step 5: Solve for x
    x = 485,117.20/809.91
  6. Step 6: Final answer
    x = 598.98

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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.