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Finding the Fourth Proportional to 81.16, 121.56 and 65.74

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Solution

The fourth proportional to 81.16, 121.56 and 65.74 is: 98.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.16 : 121.56 = 65.74 : x
  2. Step 2: Convert to fraction form
    81.16/121.56 = 65.74/x
  3. Step 3: Cross multiply
    81.16x = 121.56 × 65.74
  4. Step 4: Simplify right side
    81.16x = 7,991.35
  5. Step 5: Solve for x
    x = 7,991.35/81.16
  6. Step 6: Final answer
    x = 98.46

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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.