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Finding the Fourth Proportional to 820.75, 1,231.67 and 387.94

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Solution

The fourth proportional to 820.75, 1,231.67 and 387.94 is: 582.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    820.75 : 1,231.67 = 387.94 : x
  2. Step 2: Convert to fraction form
    820.75/1,231.67 = 387.94/x
  3. Step 3: Cross multiply
    820.75x = 1,231.67 × 387.94
  4. Step 4: Simplify right side
    820.75x = 477,814.06
  5. Step 5: Solve for x
    x = 477,814.06/820.75
  6. Step 6: Final answer
    x = 582.17

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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.