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Finding the Fourth Proportional to 81.48, 121.55 and 79.64

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Solution

The fourth proportional to 81.48, 121.55 and 79.64 is: 118.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.48 : 121.55 = 79.64 : x
  2. Step 2: Convert to fraction form
    81.48/121.55 = 79.64/x
  3. Step 3: Cross multiply
    81.48x = 121.55 × 79.64
  4. Step 4: Simplify right side
    81.48x = 9,680.24
  5. Step 5: Solve for x
    x = 9,680.24/81.48
  6. Step 6: Final answer
    x = 118.81

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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.