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Finding the Fourth Proportional to 128.58, 177.39 and 81.94

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Solution

The fourth proportional to 128.58, 177.39 and 81.94 is: 113.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.58 : 177.39 = 81.94 : x
  2. Step 2: Convert to fraction form
    128.58/177.39 = 81.94/x
  3. Step 3: Cross multiply
    128.58x = 177.39 × 81.94
  4. Step 4: Simplify right side
    128.58x = 14,535.34
  5. Step 5: Solve for x
    x = 14,535.34/128.58
  6. Step 6: Final answer
    x = 113.05

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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.