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Finding the Fourth Proportional to 81.16, 121.70 and 66.58

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Solution

The fourth proportional to 81.16, 121.70 and 66.58 is: 99.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.16 : 121.70 = 66.58 : x
  2. Step 2: Convert to fraction form
    81.16/121.70 = 66.58/x
  3. Step 3: Cross multiply
    81.16x = 121.70 × 66.58
  4. Step 4: Simplify right side
    81.16x = 8,102.79
  5. Step 5: Solve for x
    x = 8,102.79/81.16
  6. Step 6: Final answer
    x = 99.84

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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.