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Finding the Fourth Proportional to 128.05, 176.72 and 91.19

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Solution

The fourth proportional to 128.05, 176.72 and 91.19 is: 125.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.05 : 176.72 = 91.19 : x
  2. Step 2: Convert to fraction form
    128.05/176.72 = 91.19/x
  3. Step 3: Cross multiply
    128.05x = 176.72 × 91.19
  4. Step 4: Simplify right side
    128.05x = 16,115.10
  5. Step 5: Solve for x
    x = 16,115.10/128.05
  6. Step 6: Final answer
    x = 125.85

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.