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Finding the Fourth Proportional to 128.28, 191.64 and 82.24

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Solution

The fourth proportional to 128.28, 191.64 and 82.24 is: 122.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.28 : 191.64 = 82.24 : x
  2. Step 2: Convert to fraction form
    128.28/191.64 = 82.24/x
  3. Step 3: Cross multiply
    128.28x = 191.64 × 82.24
  4. Step 4: Simplify right side
    128.28x = 15,760.47
  5. Step 5: Solve for x
    x = 15,760.47/128.28
  6. Step 6: Final answer
    x = 122.86

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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.