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Finding the Fourth Proportional to 641.28, 885 and 420.36

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Solution

The fourth proportional to 641.28, 885 and 420.36 is: 580.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    641.28 : 885 = 420.36 : x
  2. Step 2: Convert to fraction form
    641.28/885 = 420.36/x
  3. Step 3: Cross multiply
    641.28x = 885 × 420.36
  4. Step 4: Simplify right side
    641.28x = 372,018.60
  5. Step 5: Solve for x
    x = 372,018.60/641.28
  6. Step 6: Final answer
    x = 580.12

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.