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Finding the Fourth Proportional to 641.96, 885.57 and 420.80

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Solution

The fourth proportional to 641.96, 885.57 and 420.80 is: 580.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    641.96 : 885.57 = 420.80 : x
  2. Step 2: Convert to fraction form
    641.96/885.57 = 420.80/x
  3. Step 3: Cross multiply
    641.96x = 885.57 × 420.80
  4. Step 4: Simplify right side
    641.96x = 372,647.86
  5. Step 5: Solve for x
    x = 372,647.86/641.96
  6. Step 6: Final answer
    x = 580.48

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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.