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Finding the Fourth Proportional to 128.35, 177.11 and 86.88

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Solution

The fourth proportional to 128.35, 177.11 and 86.88 is: 119.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.35 : 177.11 = 86.88 : x
  2. Step 2: Convert to fraction form
    128.35/177.11 = 86.88/x
  3. Step 3: Cross multiply
    128.35x = 177.11 × 86.88
  4. Step 4: Simplify right side
    128.35x = 15,387.32
  5. Step 5: Solve for x
    x = 15,387.32/128.35
  6. Step 6: Final answer
    x = 119.89

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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.