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Finding the Fourth Proportional to 128, 191.86 and 76.62

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Solution

The fourth proportional to 128, 191.86 and 76.62 is: 114.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    128 : 191.86 = 76.62 : x
  2. Step 2: Convert to fraction form
    128/191.86 = 76.62/x
  3. Step 3: Cross multiply
    128x = 191.86 × 76.62
  4. Step 4: Simplify right side
    128x = 14,700.31
  5. Step 5: Solve for x
    x = 14,700.31/128
  6. Step 6: Final answer
    x = 114.85

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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.