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Finding the Fourth Proportional to 128.54, 192.95 and 80.55

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Solution

The fourth proportional to 128.54, 192.95 and 80.55 is: 120.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.54 : 192.95 = 80.55 : x
  2. Step 2: Convert to fraction form
    128.54/192.95 = 80.55/x
  3. Step 3: Cross multiply
    128.54x = 192.95 × 80.55
  4. Step 4: Simplify right side
    128.54x = 15,541.72
  5. Step 5: Solve for x
    x = 15,541.72/128.54
  6. Step 6: Final answer
    x = 120.91

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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.