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Finding the Fourth Proportional to 84.60, 126.75 and 81.78

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Solution

The fourth proportional to 84.60, 126.75 and 81.78 is: 122.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    84.60 : 126.75 = 81.78 : x
  2. Step 2: Convert to fraction form
    84.60/126.75 = 81.78/x
  3. Step 3: Cross multiply
    84.60x = 126.75 × 81.78
  4. Step 4: Simplify right side
    84.60x = 10,365.62
  5. Step 5: Solve for x
    x = 10,365.62/84.60
  6. Step 6: Final answer
    x = 122.53

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.