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Finding the Fourth Proportional to 81.65, 122.43 and 47.42

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Solution

The fourth proportional to 81.65, 122.43 and 47.42 is: 71.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.65 : 122.43 = 47.42 : x
  2. Step 2: Convert to fraction form
    81.65/122.43 = 47.42/x
  3. Step 3: Cross multiply
    81.65x = 122.43 × 47.42
  4. Step 4: Simplify right side
    81.65x = 5,805.83
  5. Step 5: Solve for x
    x = 5,805.83/81.65
  6. Step 6: Final answer
    x = 71.11

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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.