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Finding the Fourth Proportional to 428.74, 643.06 and 120.56

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Solution

The fourth proportional to 428.74, 643.06 and 120.56 is: 180.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.74 : 643.06 = 120.56 : x
  2. Step 2: Convert to fraction form
    428.74/643.06 = 120.56/x
  3. Step 3: Cross multiply
    428.74x = 643.06 × 120.56
  4. Step 4: Simplify right side
    428.74x = 77,527.31
  5. Step 5: Solve for x
    x = 77,527.31/428.74
  6. Step 6: Final answer
    x = 180.83

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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.