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Finding the Fourth Proportional to 781.70, 1,171.72 and 261.23

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Solution

The fourth proportional to 781.70, 1,171.72 and 261.23 is: 391.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.70 : 1,171.72 = 261.23 : x
  2. Step 2: Convert to fraction form
    781.70/1,171.72 = 261.23/x
  3. Step 3: Cross multiply
    781.70x = 1,171.72 × 261.23
  4. Step 4: Simplify right side
    781.70x = 306,081.41
  5. Step 5: Solve for x
    x = 306,081.41/781.70
  6. Step 6: Final answer
    x = 391.56

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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.