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Finding the Fourth Proportional to 57.05, 85.21 and 39.78

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Solution

The fourth proportional to 57.05, 85.21 and 39.78 is: 59.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    57.05 : 85.21 = 39.78 : x
  2. Step 2: Convert to fraction form
    57.05/85.21 = 39.78/x
  3. Step 3: Cross multiply
    57.05x = 85.21 × 39.78
  4. Step 4: Simplify right side
    57.05x = 3,389.55
  5. Step 5: Solve for x
    x = 3,389.55/57.05
  6. Step 6: Final answer
    x = 59.42

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.