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Finding the Fourth Proportional to 128.87, 178.07 and 91.97

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Solution

The fourth proportional to 128.87, 178.07 and 91.97 is: 127.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.87 : 178.07 = 91.97 : x
  2. Step 2: Convert to fraction form
    128.87/178.07 = 91.97/x
  3. Step 3: Cross multiply
    128.87x = 178.07 × 91.97
  4. Step 4: Simplify right side
    128.87x = 16,376.21
  5. Step 5: Solve for x
    x = 16,376.21/128.87
  6. Step 6: Final answer
    x = 127.08

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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.