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Finding the Fourth Proportional to 81.68, 111.88 and 79.36

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Solution

The fourth proportional to 81.68, 111.88 and 79.36 is: 108.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.68 : 111.88 = 79.36 : x
  2. Step 2: Convert to fraction form
    81.68/111.88 = 79.36/x
  3. Step 3: Cross multiply
    81.68x = 111.88 × 79.36
  4. Step 4: Simplify right side
    81.68x = 8,878.80
  5. Step 5: Solve for x
    x = 8,878.80/81.68
  6. Step 6: Final answer
    x = 108.70

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.