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Finding the Fourth Proportional to 57.15, 78.84 and 39.71

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Solution

The fourth proportional to 57.15, 78.84 and 39.71 is: 54.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    57.15 : 78.84 = 39.71 : x
  2. Step 2: Convert to fraction form
    57.15/78.84 = 39.71/x
  3. Step 3: Cross multiply
    57.15x = 78.84 × 39.71
  4. Step 4: Simplify right side
    57.15x = 3,130.70
  5. Step 5: Solve for x
    x = 3,130.70/57.15
  6. Step 6: Final answer
    x = 54.78

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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.