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Finding the Fourth Proportional to 15.09, 20.78 and 12.88

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Solution

The fourth proportional to 15.09, 20.78 and 12.88 is: 17.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    15.09 : 20.78 = 12.88 : x
  2. Step 2: Convert to fraction form
    15.09/20.78 = 12.88/x
  3. Step 3: Cross multiply
    15.09x = 20.78 × 12.88
  4. Step 4: Simplify right side
    15.09x = 267.75
  5. Step 5: Solve for x
    x = 267.75/15.09
  6. Step 6: Final answer
    x = 17.75

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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.