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Finding the Fourth Proportional to 84.72, 126.38 and 81.66

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Solution

The fourth proportional to 84.72, 126.38 and 81.66 is: 121.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    84.72 : 126.38 = 81.66 : x
  2. Step 2: Convert to fraction form
    84.72/126.38 = 81.66/x
  3. Step 3: Cross multiply
    84.72x = 126.38 × 81.66
  4. Step 4: Simplify right side
    84.72x = 10,320.19
  5. Step 5: Solve for x
    x = 10,320.19/84.72
  6. Step 6: Final answer
    x = 121.82

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.