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Finding the Fourth Proportional to 81, 111.68 and 66.32

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Solution

The fourth proportional to 81, 111.68 and 66.32 is: 91.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    81 : 111.68 = 66.32 : x
  2. Step 2: Convert to fraction form
    81/111.68 = 66.32/x
  3. Step 3: Cross multiply
    81x = 111.68 × 66.32
  4. Step 4: Simplify right side
    81x = 7,406.40
  5. Step 5: Solve for x
    x = 7,406.40/81
  6. Step 6: Final answer
    x = 91.44

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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.