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Finding the Fourth Proportional to 128.70, 177.68 and 82.12

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Solution

The fourth proportional to 128.70, 177.68 and 82.12 is: 113.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.70 : 177.68 = 82.12 : x
  2. Step 2: Convert to fraction form
    128.70/177.68 = 82.12/x
  3. Step 3: Cross multiply
    128.70x = 177.68 × 82.12
  4. Step 4: Simplify right side
    128.70x = 14,591.08
  5. Step 5: Solve for x
    x = 14,591.08/128.70
  6. Step 6: Final answer
    x = 113.37

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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.