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Finding the Fourth Proportional to 128.66, 192.75 and 85.94

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Solution

The fourth proportional to 128.66, 192.75 and 85.94 is: 128.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.66 : 192.75 = 85.94 : x
  2. Step 2: Convert to fraction form
    128.66/192.75 = 85.94/x
  3. Step 3: Cross multiply
    128.66x = 192.75 × 85.94
  4. Step 4: Simplify right side
    128.66x = 16,564.94
  5. Step 5: Solve for x
    x = 16,564.94/128.66
  6. Step 6: Final answer
    x = 128.75

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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.