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Finding the Fourth Proportional to 57.12, 85.52 and 39.90

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Solution

The fourth proportional to 57.12, 85.52 and 39.90 is: 59.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    57.12 : 85.52 = 39.90 : x
  2. Step 2: Convert to fraction form
    57.12/85.52 = 39.90/x
  3. Step 3: Cross multiply
    57.12x = 85.52 × 39.90
  4. Step 4: Simplify right side
    57.12x = 3,412.25
  5. Step 5: Solve for x
    x = 3,412.25/57.12
  6. Step 6: Final answer
    x = 59.74

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.