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Finding the Fourth Proportional to 21.15, 29.18 and 12.97

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Solution

The fourth proportional to 21.15, 29.18 and 12.97 is: 17.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.15 : 29.18 = 12.97 : x
  2. Step 2: Convert to fraction form
    21.15/29.18 = 12.97/x
  3. Step 3: Cross multiply
    21.15x = 29.18 × 12.97
  4. Step 4: Simplify right side
    21.15x = 378.46
  5. Step 5: Solve for x
    x = 378.46/21.15
  6. Step 6: Final answer
    x = 17.89

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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.