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Finding the Fourth Proportional to 812.56, 1,121.70 and 518.20

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Solution

The fourth proportional to 812.56, 1,121.70 and 518.20 is: 715.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    812.56 : 1,121.70 = 518.20 : x
  2. Step 2: Convert to fraction form
    812.56/1,121.70 = 518.20/x
  3. Step 3: Cross multiply
    812.56x = 1,121.70 × 518.20
  4. Step 4: Simplify right side
    812.56x = 581,264.94
  5. Step 5: Solve for x
    x = 581,264.94/812.56
  6. Step 6: Final answer
    x = 715.35

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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.