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Finding the Fourth Proportional to 820.86, 1,231.76 and 491.89

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Solution

The fourth proportional to 820.86, 1,231.76 and 491.89 is: 738.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    820.86 : 1,231.76 = 491.89 : x
  2. Step 2: Convert to fraction form
    820.86/1,231.76 = 491.89/x
  3. Step 3: Cross multiply
    820.86x = 1,231.76 × 491.89
  4. Step 4: Simplify right side
    820.86x = 605,890.43
  5. Step 5: Solve for x
    x = 605,890.43/820.86
  6. Step 6: Final answer
    x = 738.12

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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.