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Finding the Fourth Proportional to 15, 20.72 and 12.95

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Solution

The fourth proportional to 15, 20.72 and 12.95 is: 17.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    15 : 20.72 = 12.95 : x
  2. Step 2: Convert to fraction form
    15/20.72 = 12.95/x
  3. Step 3: Cross multiply
    15x = 20.72 × 12.95
  4. Step 4: Simplify right side
    15x = 268.32
  5. Step 5: Solve for x
    x = 268.32/15
  6. Step 6: Final answer
    x = 17.89

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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.