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Finding the Fourth Proportional to 509.76, 764.16 and 428.76

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Solution

The fourth proportional to 509.76, 764.16 and 428.76 is: 642.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    509.76 : 764.16 = 428.76 : x
  2. Step 2: Convert to fraction form
    509.76/764.16 = 428.76/x
  3. Step 3: Cross multiply
    509.76x = 764.16 × 428.76
  4. Step 4: Simplify right side
    509.76x = 327,641.24
  5. Step 5: Solve for x
    x = 327,641.24/509.76
  6. Step 6: Final answer
    x = 642.74

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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.