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Finding the Fourth Proportional to 839.41, 1,259.21 and 428.56

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Solution

The fourth proportional to 839.41, 1,259.21 and 428.56 is: 642.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    839.41 : 1,259.21 = 428.56 : x
  2. Step 2: Convert to fraction form
    839.41/1,259.21 = 428.56/x
  3. Step 3: Cross multiply
    839.41x = 1,259.21 × 428.56
  4. Step 4: Simplify right side
    839.41x = 539,647.04
  5. Step 5: Solve for x
    x = 539,647.04/839.41
  6. Step 6: Final answer
    x = 642.89

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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.