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Finding the Fourth Proportional to 679.47, 1,018.36 and 387.21

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Solution

The fourth proportional to 679.47, 1,018.36 and 387.21 is: 580.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    679.47 : 1,018.36 = 387.21 : x
  2. Step 2: Convert to fraction form
    679.47/1,018.36 = 387.21/x
  3. Step 3: Cross multiply
    679.47x = 1,018.36 × 387.21
  4. Step 4: Simplify right side
    679.47x = 394,323.48
  5. Step 5: Solve for x
    x = 394,323.48/679.47
  6. Step 6: Final answer
    x = 580.34

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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.