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Finding the Fourth Proportional to 81.49, 121.63 and 66.31

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Solution

The fourth proportional to 81.49, 121.63 and 66.31 is: 98.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.49 : 121.63 = 66.31 : x
  2. Step 2: Convert to fraction form
    81.49/121.63 = 66.31/x
  3. Step 3: Cross multiply
    81.49x = 121.63 × 66.31
  4. Step 4: Simplify right side
    81.49x = 8,065.29
  5. Step 5: Solve for x
    x = 8,065.29/81.49
  6. Step 6: Final answer
    x = 98.97

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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.