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Finding the Fourth Proportional to 820.86, 1,231.21 and 659.56

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Solution

The fourth proportional to 820.86, 1,231.21 and 659.56 is: 989.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    820.86 : 1,231.21 = 659.56 : x
  2. Step 2: Convert to fraction form
    820.86/1,231.21 = 659.56/x
  3. Step 3: Cross multiply
    820.86x = 1,231.21 × 659.56
  4. Step 4: Simplify right side
    820.86x = 812,056.87
  5. Step 5: Solve for x
    x = 812,056.87/820.86
  6. Step 6: Final answer
    x = 989.28

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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.