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Finding the Fourth Proportional to 781.23, 1,171.47 and 415.92

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Solution

The fourth proportional to 781.23, 1,171.47 and 415.92 is: 623.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.23 : 1,171.47 = 415.92 : x
  2. Step 2: Convert to fraction form
    781.23/1,171.47 = 415.92/x
  3. Step 3: Cross multiply
    781.23x = 1,171.47 × 415.92
  4. Step 4: Simplify right side
    781.23x = 487,243.76
  5. Step 5: Solve for x
    x = 487,243.76/781.23
  6. Step 6: Final answer
    x = 623.68

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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.