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Finding the Fourth Proportional to 139.91, 193.09 and 128.75

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Solution

The fourth proportional to 139.91, 193.09 and 128.75 is: 177.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.91 : 193.09 = 128.75 : x
  2. Step 2: Convert to fraction form
    139.91/193.09 = 128.75/x
  3. Step 3: Cross multiply
    139.91x = 193.09 × 128.75
  4. Step 4: Simplify right side
    139.91x = 24,860.34
  5. Step 5: Solve for x
    x = 24,860.34/139.91
  6. Step 6: Final answer
    x = 177.69

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.