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Finding the Fourth Proportional to 81.16, 121.78 and 75.54

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Solution

The fourth proportional to 81.16, 121.78 and 75.54 is: 113.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.16 : 121.78 = 75.54 : x
  2. Step 2: Convert to fraction form
    81.16/121.78 = 75.54/x
  3. Step 3: Cross multiply
    81.16x = 121.78 × 75.54
  4. Step 4: Simplify right side
    81.16x = 9,199.26
  5. Step 5: Solve for x
    x = 9,199.26/81.16
  6. Step 6: Final answer
    x = 113.35

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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.