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Finding the Fourth Proportional to 89.85, 134.64 and 81.75

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Solution

The fourth proportional to 89.85, 134.64 and 81.75 is: 122.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    89.85 : 134.64 = 81.75 : x
  2. Step 2: Convert to fraction form
    89.85/134.64 = 81.75/x
  3. Step 3: Cross multiply
    89.85x = 134.64 × 81.75
  4. Step 4: Simplify right side
    89.85x = 11,006.82
  5. Step 5: Solve for x
    x = 11,006.82/89.85
  6. Step 6: Final answer
    x = 122.50

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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.