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Finding the Fourth Proportional to 428.78, 643.41 and 397.80

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Solution

The fourth proportional to 428.78, 643.41 and 397.80 is: 596.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.78 : 643.41 = 397.80 : x
  2. Step 2: Convert to fraction form
    428.78/643.41 = 397.80/x
  3. Step 3: Cross multiply
    428.78x = 643.41 × 397.80
  4. Step 4: Simplify right side
    428.78x = 255,948.50
  5. Step 5: Solve for x
    x = 255,948.50/428.78
  6. Step 6: Final answer
    x = 596.92

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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.