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Finding the Fourth Proportional to 81.91, 113.07 and 64.47

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Solution

The fourth proportional to 81.91, 113.07 and 64.47 is: 89.00

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.91 : 113.07 = 64.47 : x
  2. Step 2: Convert to fraction form
    81.91/113.07 = 64.47/x
  3. Step 3: Cross multiply
    81.91x = 113.07 × 64.47
  4. Step 4: Simplify right side
    81.91x = 7,289.62
  5. Step 5: Solve for x
    x = 7,289.62/81.91
  6. Step 6: Final answer
    x = 89.00

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.