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Finding the Fourth Proportional to 813.70, 1,122.54 and 639.55

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Solution

The fourth proportional to 813.70, 1,122.54 and 639.55 is: 882.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    813.70 : 1,122.54 = 639.55 : x
  2. Step 2: Convert to fraction form
    813.70/1,122.54 = 639.55/x
  3. Step 3: Cross multiply
    813.70x = 1,122.54 × 639.55
  4. Step 4: Simplify right side
    813.70x = 717,920.46
  5. Step 5: Solve for x
    x = 717,920.46/813.70
  6. Step 6: Final answer
    x = 882.29

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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.