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Finding the Fourth Proportional to 81.19, 121.78 and 20.32

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Solution

The fourth proportional to 81.19, 121.78 and 20.32 is: 30.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.19 : 121.78 = 20.32 : x
  2. Step 2: Convert to fraction form
    81.19/121.78 = 20.32/x
  3. Step 3: Cross multiply
    81.19x = 121.78 × 20.32
  4. Step 4: Simplify right side
    81.19x = 2,473.86
  5. Step 5: Solve for x
    x = 2,473.86/81.19
  6. Step 6: Final answer
    x = 30.47

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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.