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Finding the Fourth Proportional to 20.91, 31.32 and 14.15

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Solution

The fourth proportional to 20.91, 31.32 and 14.15 is: 21.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.91 : 31.32 = 14.15 : x
  2. Step 2: Convert to fraction form
    20.91/31.32 = 14.15/x
  3. Step 3: Cross multiply
    20.91x = 31.32 × 14.15
  4. Step 4: Simplify right side
    20.91x = 443.18
  5. Step 5: Solve for x
    x = 443.18/20.91
  6. Step 6: Final answer
    x = 21.19

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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.