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Finding the Fourth Proportional to 21.91, 30.23 and 13.72

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Solution

The fourth proportional to 21.91, 30.23 and 13.72 is: 18.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.91 : 30.23 = 13.72 : x
  2. Step 2: Convert to fraction form
    21.91/30.23 = 13.72/x
  3. Step 3: Cross multiply
    21.91x = 30.23 × 13.72
  4. Step 4: Simplify right side
    21.91x = 414.76
  5. Step 5: Solve for x
    x = 414.76/21.91
  6. Step 6: Final answer
    x = 18.93

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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.