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Finding the Fourth Proportional to 81.60, 121.78 and 79.44

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Solution

The fourth proportional to 81.60, 121.78 and 79.44 is: 118.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.60 : 121.78 = 79.44 : x
  2. Step 2: Convert to fraction form
    81.60/121.78 = 79.44/x
  3. Step 3: Cross multiply
    81.60x = 121.78 × 79.44
  4. Step 4: Simplify right side
    81.60x = 9,674.20
  5. Step 5: Solve for x
    x = 9,674.20/81.60
  6. Step 6: Final answer
    x = 118.56

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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.