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Finding the Fourth Proportional to 81.07, 111.99 and 71.21

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Solution

The fourth proportional to 81.07, 111.99 and 71.21 is: 98.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.07 : 111.99 = 71.21 : x
  2. Step 2: Convert to fraction form
    81.07/111.99 = 71.21/x
  3. Step 3: Cross multiply
    81.07x = 111.99 × 71.21
  4. Step 4: Simplify right side
    81.07x = 7,974.81
  5. Step 5: Solve for x
    x = 7,974.81/81.07
  6. Step 6: Final answer
    x = 98.37

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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.