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Finding the Fourth Proportional to 21.85, 30.17 and 15.71

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Solution

The fourth proportional to 21.85, 30.17 and 15.71 is: 21.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.85 : 30.17 = 15.71 : x
  2. Step 2: Convert to fraction form
    21.85/30.17 = 15.71/x
  3. Step 3: Cross multiply
    21.85x = 30.17 × 15.71
  4. Step 4: Simplify right side
    21.85x = 473.86
  5. Step 5: Solve for x
    x = 473.86/21.85
  6. Step 6: Final answer
    x = 21.69

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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.