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Finding the Fourth Proportional to 20.45, 28.20 and 12.57

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Solution

The fourth proportional to 20.45, 28.20 and 12.57 is: 17.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.45 : 28.20 = 12.57 : x
  2. Step 2: Convert to fraction form
    20.45/28.20 = 12.57/x
  3. Step 3: Cross multiply
    20.45x = 28.20 × 12.57
  4. Step 4: Simplify right side
    20.45x = 354.47
  5. Step 5: Solve for x
    x = 354.47/20.45
  6. Step 6: Final answer
    x = 17.33

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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.