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Finding the Fourth Proportional to 57.72, 86.57 and 19.20

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Solution

The fourth proportional to 57.72, 86.57 and 19.20 is: 28.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    57.72 : 86.57 = 19.20 : x
  2. Step 2: Convert to fraction form
    57.72/86.57 = 19.20/x
  3. Step 3: Cross multiply
    57.72x = 86.57 × 19.20
  4. Step 4: Simplify right side
    57.72x = 1,662.52
  5. Step 5: Solve for x
    x = 1,662.52/57.72
  6. Step 6: Final answer
    x = 28.80

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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.