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Finding the Fourth Proportional to 128.20, 191.33 and 117.70

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Solution

The fourth proportional to 128.20, 191.33 and 117.70 is: 175.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.20 : 191.33 = 117.70 : x
  2. Step 2: Convert to fraction form
    128.20/191.33 = 117.70/x
  3. Step 3: Cross multiply
    128.20x = 191.33 × 117.70
  4. Step 4: Simplify right side
    128.20x = 22,519.54
  5. Step 5: Solve for x
    x = 22,519.54/128.20
  6. Step 6: Final answer
    x = 175.66

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.