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Finding the Fourth Proportional to 57.12, 78.84 and 39.69

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Solution

The fourth proportional to 57.12, 78.84 and 39.69 is: 54.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    57.12 : 78.84 = 39.69 : x
  2. Step 2: Convert to fraction form
    57.12/78.84 = 39.69/x
  3. Step 3: Cross multiply
    57.12x = 78.84 × 39.69
  4. Step 4: Simplify right side
    57.12x = 3,128.57
  5. Step 5: Solve for x
    x = 3,128.57/57.12
  6. Step 6: Final answer
    x = 54.77

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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.