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Finding the Fourth Proportional to 81.40, 121.98 and 74.56

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Solution

The fourth proportional to 81.40, 121.98 and 74.56 is: 111.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.40 : 121.98 = 74.56 : x
  2. Step 2: Convert to fraction form
    81.40/121.98 = 74.56/x
  3. Step 3: Cross multiply
    81.40x = 121.98 × 74.56
  4. Step 4: Simplify right side
    81.40x = 9,094.83
  5. Step 5: Solve for x
    x = 9,094.83/81.40
  6. Step 6: Final answer
    x = 111.73

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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.