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Finding the Fourth Proportional to 814.16, 1,122.81 and 639.20

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Solution

The fourth proportional to 814.16, 1,122.81 and 639.20 is: 881.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    814.16 : 1,122.81 = 639.20 : x
  2. Step 2: Convert to fraction form
    814.16/1,122.81 = 639.20/x
  3. Step 3: Cross multiply
    814.16x = 1,122.81 × 639.20
  4. Step 4: Simplify right side
    814.16x = 717,698.94
  5. Step 5: Solve for x
    x = 717,698.94/814.16
  6. Step 6: Final answer
    x = 881.52

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.