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Finding the Fourth Proportional to 911.78, 1,258.11 and 518.81

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Solution

The fourth proportional to 911.78, 1,258.11 and 518.81 is: 715.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    911.78 : 1,258.11 = 518.81 : x
  2. Step 2: Convert to fraction form
    911.78/1,258.11 = 518.81/x
  3. Step 3: Cross multiply
    911.78x = 1,258.11 × 518.81
  4. Step 4: Simplify right side
    911.78x = 652,720.05
  5. Step 5: Solve for x
    x = 652,720.05/911.78
  6. Step 6: Final answer
    x = 715.87

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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.