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Finding the Fourth Proportional to 31.28, 43.20 and 21.62

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Solution

The fourth proportional to 31.28, 43.20 and 21.62 is: 29.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.28 : 43.20 = 21.62 : x
  2. Step 2: Convert to fraction form
    31.28/43.20 = 21.62/x
  3. Step 3: Cross multiply
    31.28x = 43.20 × 21.62
  4. Step 4: Simplify right side
    31.28x = 933.98
  5. Step 5: Solve for x
    x = 933.98/31.28
  6. Step 6: Final answer
    x = 29.86

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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.