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Finding the Fourth Proportional to 31.29, 43.16 and 20.90

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Solution

The fourth proportional to 31.29, 43.16 and 20.90 is: 28.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.29 : 43.16 = 20.90 : x
  2. Step 2: Convert to fraction form
    31.29/43.16 = 20.90/x
  3. Step 3: Cross multiply
    31.29x = 43.16 × 20.90
  4. Step 4: Simplify right side
    31.29x = 901.72
  5. Step 5: Solve for x
    x = 901.72/31.29
  6. Step 6: Final answer
    x = 28.82

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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.