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Finding the Fourth Proportional to 21.68, 29.90 and 12.47

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Solution

The fourth proportional to 21.68, 29.90 and 12.47 is: 17.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.68 : 29.90 = 12.47 : x
  2. Step 2: Convert to fraction form
    21.68/29.90 = 12.47/x
  3. Step 3: Cross multiply
    21.68x = 29.90 × 12.47
  4. Step 4: Simplify right side
    21.68x = 372.73
  5. Step 5: Solve for x
    x = 372.73/21.68
  6. Step 6: Final answer
    x = 17.20

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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.