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Finding the Fourth Proportional to 823.90, 1,235.40 and 391.09

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Solution

The fourth proportional to 823.90, 1,235.40 and 391.09 is: 586.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    823.90 : 1,235.40 = 391.09 : x
  2. Step 2: Convert to fraction form
    823.90/1,235.40 = 391.09/x
  3. Step 3: Cross multiply
    823.90x = 1,235.40 × 391.09
  4. Step 4: Simplify right side
    823.90x = 483,152.59
  5. Step 5: Solve for x
    x = 483,152.59/823.90
  6. Step 6: Final answer
    x = 586.42

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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.