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Finding the Fourth Proportional to 81.45, 121.46 and 66.15

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Solution

The fourth proportional to 81.45, 121.46 and 66.15 is: 98.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.45 : 121.46 = 66.15 : x
  2. Step 2: Convert to fraction form
    81.45/121.46 = 66.15/x
  3. Step 3: Cross multiply
    81.45x = 121.46 × 66.15
  4. Step 4: Simplify right side
    81.45x = 8,034.25
  5. Step 5: Solve for x
    x = 8,034.25/81.45
  6. Step 6: Final answer
    x = 98.64

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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.