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Finding the Fourth Proportional to 57.20, 78.97 and 39.81

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Solution

The fourth proportional to 57.20, 78.97 and 39.81 is: 54.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    57.20 : 78.97 = 39.81 : x
  2. Step 2: Convert to fraction form
    57.20/78.97 = 39.81/x
  3. Step 3: Cross multiply
    57.20x = 78.97 × 39.81
  4. Step 4: Simplify right side
    57.20x = 3,143.80
  5. Step 5: Solve for x
    x = 3,143.80/57.20
  6. Step 6: Final answer
    x = 54.96

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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.