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Finding the Fourth Proportional to 57.11, 78.72 and 39.65

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Solution

The fourth proportional to 57.11, 78.72 and 39.65 is: 54.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    57.11 : 78.72 = 39.65 : x
  2. Step 2: Convert to fraction form
    57.11/78.72 = 39.65/x
  3. Step 3: Cross multiply
    57.11x = 78.72 × 39.65
  4. Step 4: Simplify right side
    57.11x = 3,121.25
  5. Step 5: Solve for x
    x = 3,121.25/57.11
  6. Step 6: Final answer
    x = 54.65

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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.