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Finding the Fourth Proportional to 671.78, 1,007.76 and 261.21

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Solution

The fourth proportional to 671.78, 1,007.76 and 261.21 is: 391.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    671.78 : 1,007.76 = 261.21 : x
  2. Step 2: Convert to fraction form
    671.78/1,007.76 = 261.21/x
  3. Step 3: Cross multiply
    671.78x = 1,007.76 × 261.21
  4. Step 4: Simplify right side
    671.78x = 263,236.99
  5. Step 5: Solve for x
    x = 263,236.99/671.78
  6. Step 6: Final answer
    x = 391.85

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.