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Finding the Fourth Proportional to 21.74, 30.00 and 13.56

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Solution

The fourth proportional to 21.74, 30.00 and 13.56 is: 18.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.74 : 30.00 = 13.56 : x
  2. Step 2: Convert to fraction form
    21.74/30.00 = 13.56/x
  3. Step 3: Cross multiply
    21.74x = 30.00 × 13.56
  4. Step 4: Simplify right side
    21.74x = 406.74
  5. Step 5: Solve for x
    x = 406.74/21.74
  6. Step 6: Final answer
    x = 18.71

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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.