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Finding the Fourth Proportional to 821.25, 1,231.23 and 430.74

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Solution

The fourth proportional to 821.25, 1,231.23 and 430.74 is: 645.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    821.25 : 1,231.23 = 430.74 : x
  2. Step 2: Convert to fraction form
    821.25/1,231.23 = 430.74/x
  3. Step 3: Cross multiply
    821.25x = 1,231.23 × 430.74
  4. Step 4: Simplify right side
    821.25x = 530,340.01
  5. Step 5: Solve for x
    x = 530,340.01/821.25
  6. Step 6: Final answer
    x = 645.77

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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.