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Finding the Fourth Proportional to 21.11, 31.66 and 18.88

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Solution

The fourth proportional to 21.11, 31.66 and 18.88 is: 28.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.11 : 31.66 = 18.88 : x
  2. Step 2: Convert to fraction form
    21.11/31.66 = 18.88/x
  3. Step 3: Cross multiply
    21.11x = 31.66 × 18.88
  4. Step 4: Simplify right side
    21.11x = 597.61
  5. Step 5: Solve for x
    x = 597.61/21.11
  6. Step 6: Final answer
    x = 28.32

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.