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Finding the Fourth Proportional to 839.11, 1,258.97 and 428.44

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Solution

The fourth proportional to 839.11, 1,258.97 and 428.44 is: 642.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    839.11 : 1,258.97 = 428.44 : x
  2. Step 2: Convert to fraction form
    839.11/1,258.97 = 428.44/x
  3. Step 3: Cross multiply
    839.11x = 1,258.97 × 428.44
  4. Step 4: Simplify right side
    839.11x = 539,393.11
  5. Step 5: Solve for x
    x = 539,393.11/839.11
  6. Step 6: Final answer
    x = 642.82

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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.