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Finding the Fourth Proportional to 820.79, 1,231.80 and 455.69

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Solution

The fourth proportional to 820.79, 1,231.80 and 455.69 is: 683.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    820.79 : 1,231.80 = 455.69 : x
  2. Step 2: Convert to fraction form
    820.79/1,231.80 = 455.69/x
  3. Step 3: Cross multiply
    820.79x = 1,231.80 × 455.69
  4. Step 4: Simplify right side
    820.79x = 561,318.94
  5. Step 5: Solve for x
    x = 561,318.94/820.79
  6. Step 6: Final answer
    x = 683.88

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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.