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Finding the Fourth Proportional to 91.39, 136.85 and 76.87

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Solution

The fourth proportional to 91.39, 136.85 and 76.87 is: 115.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.39 : 136.85 = 76.87 : x
  2. Step 2: Convert to fraction form
    91.39/136.85 = 76.87/x
  3. Step 3: Cross multiply
    91.39x = 136.85 × 76.87
  4. Step 4: Simplify right side
    91.39x = 10,519.66
  5. Step 5: Solve for x
    x = 10,519.66/91.39
  6. Step 6: Final answer
    x = 115.11

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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.