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Finding the Fourth Proportional to 15.36, 21.12 and 12.88

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Solution

The fourth proportional to 15.36, 21.12 and 12.88 is: 17.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    15.36 : 21.12 = 12.88 : x
  2. Step 2: Convert to fraction form
    15.36/21.12 = 12.88/x
  3. Step 3: Cross multiply
    15.36x = 21.12 × 12.88
  4. Step 4: Simplify right side
    15.36x = 272.03
  5. Step 5: Solve for x
    x = 272.03/15.36
  6. Step 6: Final answer
    x = 17.71

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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.