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Finding the Fourth Proportional to 678.09, 1,018.26 and 423.21

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Solution

The fourth proportional to 678.09, 1,018.26 and 423.21 is: 635.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.09 : 1,018.26 = 423.21 : x
  2. Step 2: Convert to fraction form
    678.09/1,018.26 = 423.21/x
  3. Step 3: Cross multiply
    678.09x = 1,018.26 × 423.21
  4. Step 4: Simplify right side
    678.09x = 430,930.61
  5. Step 5: Solve for x
    x = 430,930.61/678.09
  6. Step 6: Final answer
    x = 635.51

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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.