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Finding the Fourth Proportional to 128.49, 192.66 and 81.59

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Solution

The fourth proportional to 128.49, 192.66 and 81.59 is: 122.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.49 : 192.66 = 81.59 : x
  2. Step 2: Convert to fraction form
    128.49/192.66 = 81.59/x
  3. Step 3: Cross multiply
    128.49x = 192.66 × 81.59
  4. Step 4: Simplify right side
    128.49x = 15,718.17
  5. Step 5: Solve for x
    x = 15,718.17/128.49
  6. Step 6: Final answer
    x = 122.33

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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.