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Finding the Fourth Proportional to 81.46, 111.90 and 65.85

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Solution

The fourth proportional to 81.46, 111.90 and 65.85 is: 90.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.46 : 111.90 = 65.85 : x
  2. Step 2: Convert to fraction form
    81.46/111.90 = 65.85/x
  3. Step 3: Cross multiply
    81.46x = 111.90 × 65.85
  4. Step 4: Simplify right side
    81.46x = 7,368.62
  5. Step 5: Solve for x
    x = 7,368.62/81.46
  6. Step 6: Final answer
    x = 90.46

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.