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Finding the Fourth Proportional to 609.45, 839.90 and 420.45

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Solution

The fourth proportional to 609.45, 839.90 and 420.45 is: 579.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    609.45 : 839.90 = 420.45 : x
  2. Step 2: Convert to fraction form
    609.45/839.90 = 420.45/x
  3. Step 3: Cross multiply
    609.45x = 839.90 × 420.45
  4. Step 4: Simplify right side
    609.45x = 353,137.01
  5. Step 5: Solve for x
    x = 353,137.01/609.45
  6. Step 6: Final answer
    x = 579.44

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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.