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Finding the Fourth Proportional to 128, 191.83 and 87.68

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Solution

The fourth proportional to 128, 191.83 and 87.68 is: 131.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    128 : 191.83 = 87.68 : x
  2. Step 2: Convert to fraction form
    128/191.83 = 87.68/x
  3. Step 3: Cross multiply
    128x = 191.83 × 87.68
  4. Step 4: Simplify right side
    128x = 16,819.65
  5. Step 5: Solve for x
    x = 16,819.65/128
  6. Step 6: Final answer
    x = 131.40

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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.