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Finding the Fourth Proportional to 641.49, 885.67 and 420.80

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Solution

The fourth proportional to 641.49, 885.67 and 420.80 is: 580.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    641.49 : 885.67 = 420.80 : x
  2. Step 2: Convert to fraction form
    641.49/885.67 = 420.80/x
  3. Step 3: Cross multiply
    641.49x = 885.67 × 420.80
  4. Step 4: Simplify right side
    641.49x = 372,684.46
  5. Step 5: Solve for x
    x = 372,684.46/641.49
  6. Step 6: Final answer
    x = 580.97

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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.