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Finding the Fourth Proportional to 812.70, 1,121.09 and 615.87

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Solution

The fourth proportional to 812.70, 1,121.09 and 615.87 is: 849.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    812.70 : 1,121.09 = 615.87 : x
  2. Step 2: Convert to fraction form
    812.70/1,121.09 = 615.87/x
  3. Step 3: Cross multiply
    812.70x = 1,121.09 × 615.87
  4. Step 4: Simplify right side
    812.70x = 690,442.62
  5. Step 5: Solve for x
    x = 690,442.62/812.70
  6. Step 6: Final answer
    x = 849.57

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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.