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Finding the Fourth Proportional to 781.86, 1,171.90 and 261.74

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Solution

The fourth proportional to 781.86, 1,171.90 and 261.74 is: 392.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.86 : 1,171.90 = 261.74 : x
  2. Step 2: Convert to fraction form
    781.86/1,171.90 = 261.74/x
  3. Step 3: Cross multiply
    781.86x = 1,171.90 × 261.74
  4. Step 4: Simplify right side
    781.86x = 306,725.94
  5. Step 5: Solve for x
    x = 306,725.94/781.86
  6. Step 6: Final answer
    x = 392.31

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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.