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Finding the Fourth Proportional to 15.61, 21.56 and 13.56

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Solution

The fourth proportional to 15.61, 21.56 and 13.56 is: 18.73

Step by Step Solution

  1. Step 1: Write the proportion equation
    15.61 : 21.56 = 13.56 : x
  2. Step 2: Convert to fraction form
    15.61/21.56 = 13.56/x
  3. Step 3: Cross multiply
    15.61x = 21.56 × 13.56
  4. Step 4: Simplify right side
    15.61x = 292.35
  5. Step 5: Solve for x
    x = 292.35/15.61
  6. Step 6: Final answer
    x = 18.73

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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.