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Finding the Fourth Proportional to 81.08, 121.68 and 65

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Solution

The fourth proportional to 81.08, 121.68 and 65 is: 97.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.08 : 121.68 = 65 : x
  2. Step 2: Convert to fraction form
    81.08/121.68 = 65/x
  3. Step 3: Cross multiply
    81.08x = 121.68 × 65
  4. Step 4: Simplify right side
    81.08x = 7,909.20
  5. Step 5: Solve for x
    x = 7,909.20/81.08
  6. Step 6: Final answer
    x = 97.55

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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.