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Finding the Fourth Proportional to 428.48, 642.69 and 120.38

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Solution

The fourth proportional to 428.48, 642.69 and 120.38 is: 180.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.48 : 642.69 = 120.38 : x
  2. Step 2: Convert to fraction form
    428.48/642.69 = 120.38/x
  3. Step 3: Cross multiply
    428.48x = 642.69 × 120.38
  4. Step 4: Simplify right side
    428.48x = 77,363.81
  5. Step 5: Solve for x
    x = 77,363.81/428.48
  6. Step 6: Final answer
    x = 180.56

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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.