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Finding the Fourth Proportional to 128.97, 193.50 and 85.81

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Solution

The fourth proportional to 128.97, 193.50 and 85.81 is: 128.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.97 : 193.50 = 85.81 : x
  2. Step 2: Convert to fraction form
    128.97/193.50 = 85.81/x
  3. Step 3: Cross multiply
    128.97x = 193.50 × 85.81
  4. Step 4: Simplify right side
    128.97x = 16,604.24
  5. Step 5: Solve for x
    x = 16,604.24/128.97
  6. Step 6: Final answer
    x = 128.74

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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.