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Finding the Fourth Proportional to 821, 1,231.86 and 308.36

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Solution

The fourth proportional to 821, 1,231.86 and 308.36 is: 462.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    821 : 1,231.86 = 308.36 : x
  2. Step 2: Convert to fraction form
    821/1,231.86 = 308.36/x
  3. Step 3: Cross multiply
    821x = 1,231.86 × 308.36
  4. Step 4: Simplify right side
    821x = 379,856.35
  5. Step 5: Solve for x
    x = 379,856.35/821
  6. Step 6: Final answer
    x = 462.68

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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.