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Finding the Fourth Proportional to 31.87, 43.96 and 21.90

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Solution

The fourth proportional to 31.87, 43.96 and 21.90 is: 30.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.87 : 43.96 = 21.90 : x
  2. Step 2: Convert to fraction form
    31.87/43.96 = 21.90/x
  3. Step 3: Cross multiply
    31.87x = 43.96 × 21.90
  4. Step 4: Simplify right side
    31.87x = 962.72
  5. Step 5: Solve for x
    x = 962.72/31.87
  6. Step 6: Final answer
    x = 30.21

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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.