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Finding the Fourth Proportional to 81.20, 121.79 and 23.42

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Solution

The fourth proportional to 81.20, 121.79 and 23.42 is: 35.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.20 : 121.79 = 23.42 : x
  2. Step 2: Convert to fraction form
    81.20/121.79 = 23.42/x
  3. Step 3: Cross multiply
    81.20x = 121.79 × 23.42
  4. Step 4: Simplify right side
    81.20x = 2,851.71
  5. Step 5: Solve for x
    x = 2,851.71/81.20
  6. Step 6: Final answer
    x = 35.12

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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.