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Finding the Fourth Proportional to 428.16, 638.70 and 398.70

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Solution

The fourth proportional to 428.16, 638.70 and 398.70 is: 594.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.16 : 638.70 = 398.70 : x
  2. Step 2: Convert to fraction form
    428.16/638.70 = 398.70/x
  3. Step 3: Cross multiply
    428.16x = 638.70 × 398.70
  4. Step 4: Simplify right side
    428.16x = 254,649.69
  5. Step 5: Solve for x
    x = 254,649.69/428.16
  6. Step 6: Final answer
    x = 594.75

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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.