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Finding the Fourth Proportional to 91.76, 126.36 and 81.90

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Solution

The fourth proportional to 91.76, 126.36 and 81.90 is: 112.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.76 : 126.36 = 81.90 : x
  2. Step 2: Convert to fraction form
    91.76/126.36 = 81.90/x
  3. Step 3: Cross multiply
    91.76x = 126.36 × 81.90
  4. Step 4: Simplify right side
    91.76x = 10,348.88
  5. Step 5: Solve for x
    x = 10,348.88/91.76
  6. Step 6: Final answer
    x = 112.79

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.