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Finding the Fourth Proportional to 81.91, 112.91 and 65.54

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Solution

The fourth proportional to 81.91, 112.91 and 65.54 is: 90.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.91 : 112.91 = 65.54 : x
  2. Step 2: Convert to fraction form
    81.91/112.91 = 65.54/x
  3. Step 3: Cross multiply
    81.91x = 112.91 × 65.54
  4. Step 4: Simplify right side
    81.91x = 7,400.12
  5. Step 5: Solve for x
    x = 7,400.12/81.91
  6. Step 6: Final answer
    x = 90.34

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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.