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Finding the Fourth Proportional to 839.18, 1,259.56 and 428.61

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Solution

The fourth proportional to 839.18, 1,259.56 and 428.61 is: 643.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    839.18 : 1,259.56 = 428.61 : x
  2. Step 2: Convert to fraction form
    839.18/1,259.56 = 428.61/x
  3. Step 3: Cross multiply
    839.18x = 1,259.56 × 428.61
  4. Step 4: Simplify right side
    839.18x = 539,863.66
  5. Step 5: Solve for x
    x = 539,863.66/839.18
  6. Step 6: Final answer
    x = 643.32

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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.