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Finding the Fourth Proportional to 91.13, 136.78 and 76.85

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Solution

The fourth proportional to 91.13, 136.78 and 76.85 is: 115.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.13 : 136.78 = 76.85 : x
  2. Step 2: Convert to fraction form
    91.13/136.78 = 76.85/x
  3. Step 3: Cross multiply
    91.13x = 136.78 × 76.85
  4. Step 4: Simplify right side
    91.13x = 10,510.47
  5. Step 5: Solve for x
    x = 10,510.47/91.13
  6. Step 6: Final answer
    x = 115.33

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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.