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Finding the Fourth Proportional to 128.47, 192.79 and 82.85

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Solution

The fourth proportional to 128.47, 192.79 and 82.85 is: 124.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.47 : 192.79 = 82.85 : x
  2. Step 2: Convert to fraction form
    128.47/192.79 = 82.85/x
  3. Step 3: Cross multiply
    128.47x = 192.79 × 82.85
  4. Step 4: Simplify right side
    128.47x = 15,971.93
  5. Step 5: Solve for x
    x = 15,971.93/128.47
  6. Step 6: Final answer
    x = 124.33

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.