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Finding the Fourth Proportional to 809.91, 1,213.65 and 647.91

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Solution

The fourth proportional to 809.91, 1,213.65 and 647.91 is: 970.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    809.91 : 1,213.65 = 647.91 : x
  2. Step 2: Convert to fraction form
    809.91/1,213.65 = 647.91/x
  3. Step 3: Cross multiply
    809.91x = 1,213.65 × 647.91
  4. Step 4: Simplify right side
    809.91x = 786,335.97
  5. Step 5: Solve for x
    x = 786,335.97/809.91
  6. Step 6: Final answer
    x = 970.89

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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.