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Finding the Fourth Proportional to 21.67, 29.90 and 15.12

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Solution

The fourth proportional to 21.67, 29.90 and 15.12 is: 20.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.67 : 29.90 = 15.12 : x
  2. Step 2: Convert to fraction form
    21.67/29.90 = 15.12/x
  3. Step 3: Cross multiply
    21.67x = 29.90 × 15.12
  4. Step 4: Simplify right side
    21.67x = 452.13
  5. Step 5: Solve for x
    x = 452.13/21.67
  6. Step 6: Final answer
    x = 20.87

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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.