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Finding the Fourth Proportional to 57.20, 78.81 and 55.31

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Solution

The fourth proportional to 57.20, 78.81 and 55.31 is: 76.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    57.20 : 78.81 = 55.31 : x
  2. Step 2: Convert to fraction form
    57.20/78.81 = 55.31/x
  3. Step 3: Cross multiply
    57.20x = 78.81 × 55.31
  4. Step 4: Simplify right side
    57.20x = 4,358.59
  5. Step 5: Solve for x
    x = 4,358.59/57.20
  6. Step 6: Final answer
    x = 76.21

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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.