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Finding the Fourth Proportional to 84.87, 126.36 and 81.36

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Solution

The fourth proportional to 84.87, 126.36 and 81.36 is: 121.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    84.87 : 126.36 = 81.36 : x
  2. Step 2: Convert to fraction form
    84.87/126.36 = 81.36/x
  3. Step 3: Cross multiply
    84.87x = 126.36 × 81.36
  4. Step 4: Simplify right side
    84.87x = 10,280.65
  5. Step 5: Solve for x
    x = 10,280.65/84.87
  6. Step 6: Final answer
    x = 121.13

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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.