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Finding the Fourth Proportional to 31.38, 43.30 and 21.68

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Solution

The fourth proportional to 31.38, 43.30 and 21.68 is: 29.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.38 : 43.30 = 21.68 : x
  2. Step 2: Convert to fraction form
    31.38/43.30 = 21.68/x
  3. Step 3: Cross multiply
    31.38x = 43.30 × 21.68
  4. Step 4: Simplify right side
    31.38x = 938.74
  5. Step 5: Solve for x
    x = 938.74/31.38
  6. Step 6: Final answer
    x = 29.92

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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.