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Finding the Fourth Proportional to 128.05, 191.96 and 45.75

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Solution

The fourth proportional to 128.05, 191.96 and 45.75 is: 68.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.05 : 191.96 = 45.75 : x
  2. Step 2: Convert to fraction form
    128.05/191.96 = 45.75/x
  3. Step 3: Cross multiply
    128.05x = 191.96 × 45.75
  4. Step 4: Simplify right side
    128.05x = 8,781.32
  5. Step 5: Solve for x
    x = 8,781.32/128.05
  6. Step 6: Final answer
    x = 68.58

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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.