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Finding the Fourth Proportional to 57.47, 86.16 and 20.90

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Solution

The fourth proportional to 57.47, 86.16 and 20.90 is: 31.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    57.47 : 86.16 = 20.90 : x
  2. Step 2: Convert to fraction form
    57.47/86.16 = 20.90/x
  3. Step 3: Cross multiply
    57.47x = 86.16 × 20.90
  4. Step 4: Simplify right side
    57.47x = 1,800.31
  5. Step 5: Solve for x
    x = 1,800.31/57.47
  6. Step 6: Final answer
    x = 31.33

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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.