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Finding the Fourth Proportional to 81.65, 112.78 and 54.15

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Solution

The fourth proportional to 81.65, 112.78 and 54.15 is: 74.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.65 : 112.78 = 54.15 : x
  2. Step 2: Convert to fraction form
    81.65/112.78 = 54.15/x
  3. Step 3: Cross multiply
    81.65x = 112.78 × 54.15
  4. Step 4: Simplify right side
    81.65x = 6,106.68
  5. Step 5: Solve for x
    x = 6,106.68/81.65
  6. Step 6: Final answer
    x = 74.79

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.