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Finding the Fourth Proportional to 81.31, 121.91 and 64.14

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Solution

The fourth proportional to 81.31, 121.91 and 64.14 is: 96.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.31 : 121.91 = 64.14 : x
  2. Step 2: Convert to fraction form
    81.31/121.91 = 64.14/x
  3. Step 3: Cross multiply
    81.31x = 121.91 × 64.14
  4. Step 4: Simplify right side
    81.31x = 7,818.70
  5. Step 5: Solve for x
    x = 7,818.70/81.31
  6. Step 6: Final answer
    x = 96.17

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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.