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Finding the Fourth Proportional to 931.78, 1,285.86 and 517.78

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Solution

The fourth proportional to 931.78, 1,285.86 and 517.78 is: 714.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    931.78 : 1,285.86 = 517.78 : x
  2. Step 2: Convert to fraction form
    931.78/1,285.86 = 517.78/x
  3. Step 3: Cross multiply
    931.78x = 1,285.86 × 517.78
  4. Step 4: Simplify right side
    931.78x = 665,792.59
  5. Step 5: Solve for x
    x = 665,792.59/931.78
  6. Step 6: Final answer
    x = 714.54

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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.