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Finding the Fourth Proportional to 20.65, 28.50 and 12.88

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Solution

The fourth proportional to 20.65, 28.50 and 12.88 is: 17.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.65 : 28.50 = 12.88 : x
  2. Step 2: Convert to fraction form
    20.65/28.50 = 12.88/x
  3. Step 3: Cross multiply
    20.65x = 28.50 × 12.88
  4. Step 4: Simplify right side
    20.65x = 367.08
  5. Step 5: Solve for x
    x = 367.08/20.65
  6. Step 6: Final answer
    x = 17.78

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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.