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Finding the Fourth Proportional to 426.91, 640.34 and 118.78

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Solution

The fourth proportional to 426.91, 640.34 and 118.78 is: 178.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    426.91 : 640.34 = 118.78 : x
  2. Step 2: Convert to fraction form
    426.91/640.34 = 118.78/x
  3. Step 3: Cross multiply
    426.91x = 640.34 × 118.78
  4. Step 4: Simplify right side
    426.91x = 76,059.88
  5. Step 5: Solve for x
    x = 76,059.88/426.91
  6. Step 6: Final answer
    x = 178.16

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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.