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Finding the Fourth Proportional to 76.65, 105.81 and 54.78

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Solution

The fourth proportional to 76.65, 105.81 and 54.78 is: 75.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.65 : 105.81 = 54.78 : x
  2. Step 2: Convert to fraction form
    76.65/105.81 = 54.78/x
  3. Step 3: Cross multiply
    76.65x = 105.81 × 54.78
  4. Step 4: Simplify right side
    76.65x = 5,796.27
  5. Step 5: Solve for x
    x = 5,796.27/76.65
  6. Step 6: Final answer
    x = 75.62

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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.