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Finding the Fourth Proportional to 81.78, 123.15 and 73.76

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Solution

The fourth proportional to 81.78, 123.15 and 73.76 is: 111.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.78 : 123.15 = 73.76 : x
  2. Step 2: Convert to fraction form
    81.78/123.15 = 73.76/x
  3. Step 3: Cross multiply
    81.78x = 123.15 × 73.76
  4. Step 4: Simplify right side
    81.78x = 9,083.20
  5. Step 5: Solve for x
    x = 9,083.20/81.78
  6. Step 6: Final answer
    x = 111.07

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.