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Finding the Fourth Proportional to 81.32, 122.12 and 65.40

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Solution

The fourth proportional to 81.32, 122.12 and 65.40 is: 98.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.32 : 122.12 = 65.40 : x
  2. Step 2: Convert to fraction form
    81.32/122.12 = 65.40/x
  3. Step 3: Cross multiply
    81.32x = 122.12 × 65.40
  4. Step 4: Simplify right side
    81.32x = 7,986.65
  5. Step 5: Solve for x
    x = 7,986.65/81.32
  6. Step 6: Final answer
    x = 98.21

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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.