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Finding the Fourth Proportional to 81, 121.59 and 38.34

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Solution

The fourth proportional to 81, 121.59 and 38.34 is: 57.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    81 : 121.59 = 38.34 : x
  2. Step 2: Convert to fraction form
    81/121.59 = 38.34/x
  3. Step 3: Cross multiply
    81x = 121.59 × 38.34
  4. Step 4: Simplify right side
    81x = 4,661.76
  5. Step 5: Solve for x
    x = 4,661.76/81
  6. Step 6: Final answer
    x = 57.55

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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.