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Finding the Fourth Proportional to 428.85, 640.86 and 319.41

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Solution

The fourth proportional to 428.85, 640.86 and 319.41 is: 477.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.85 : 640.86 = 319.41 : x
  2. Step 2: Convert to fraction form
    428.85/640.86 = 319.41/x
  3. Step 3: Cross multiply
    428.85x = 640.86 × 319.41
  4. Step 4: Simplify right side
    428.85x = 204,697.09
  5. Step 5: Solve for x
    x = 204,697.09/428.85
  6. Step 6: Final answer
    x = 477.32

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.