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Finding the Fourth Proportional to 641.58, 885.60 and 420.90

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Solution

The fourth proportional to 641.58, 885.60 and 420.90 is: 580.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    641.58 : 885.60 = 420.90 : x
  2. Step 2: Convert to fraction form
    641.58/885.60 = 420.90/x
  3. Step 3: Cross multiply
    641.58x = 885.60 × 420.90
  4. Step 4: Simplify right side
    641.58x = 372,749.04
  5. Step 5: Solve for x
    x = 372,749.04/641.58
  6. Step 6: Final answer
    x = 580.99

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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.