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Finding the Fourth Proportional to 128.01, 191.67 and 86.79

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Solution

The fourth proportional to 128.01, 191.67 and 86.79 is: 129.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.01 : 191.67 = 86.79 : x
  2. Step 2: Convert to fraction form
    128.01/191.67 = 86.79/x
  3. Step 3: Cross multiply
    128.01x = 191.67 × 86.79
  4. Step 4: Simplify right side
    128.01x = 16,635.04
  5. Step 5: Solve for x
    x = 16,635.04/128.01
  6. Step 6: Final answer
    x = 129.95

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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.