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Finding the Fourth Proportional to 81.97, 112.99 and 61.21

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Solution

The fourth proportional to 81.97, 112.99 and 61.21 is: 84.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.97 : 112.99 = 61.21 : x
  2. Step 2: Convert to fraction form
    81.97/112.99 = 61.21/x
  3. Step 3: Cross multiply
    81.97x = 112.99 × 61.21
  4. Step 4: Simplify right side
    81.97x = 6,915.81
  5. Step 5: Solve for x
    x = 6,915.81/81.97
  6. Step 6: Final answer
    x = 84.38

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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.