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Finding the Fourth Proportional to 509.80, 763.90 and 428.20

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Solution

The fourth proportional to 509.80, 763.90 and 428.20 is: 641.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    509.80 : 763.90 = 428.20 : x
  2. Step 2: Convert to fraction form
    509.80/763.90 = 428.20/x
  3. Step 3: Cross multiply
    509.80x = 763.90 × 428.20
  4. Step 4: Simplify right side
    509.80x = 327,101.98
  5. Step 5: Solve for x
    x = 327,101.98/509.80
  6. Step 6: Final answer
    x = 641.63

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.