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Finding the Fourth Proportional to 128.12, 191.88 and 89.55

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Solution

The fourth proportional to 128.12, 191.88 and 89.55 is: 134.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.12 : 191.88 = 89.55 : x
  2. Step 2: Convert to fraction form
    128.12/191.88 = 89.55/x
  3. Step 3: Cross multiply
    128.12x = 191.88 × 89.55
  4. Step 4: Simplify right side
    128.12x = 17,182.85
  5. Step 5: Solve for x
    x = 17,182.85/128.12
  6. Step 6: Final answer
    x = 134.12

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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.