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Finding the Fourth Proportional to 428.98, 643.37 and 120.87

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Solution

The fourth proportional to 428.98, 643.37 and 120.87 is: 181.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.98 : 643.37 = 120.87 : x
  2. Step 2: Convert to fraction form
    428.98/643.37 = 120.87/x
  3. Step 3: Cross multiply
    428.98x = 643.37 × 120.87
  4. Step 4: Simplify right side
    428.98x = 77,760.92
  5. Step 5: Solve for x
    x = 77,760.92/428.98
  6. Step 6: Final answer
    x = 181.27

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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.