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Finding the Fourth Proportional to 21.28, 29.32 and 15.81

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Solution

The fourth proportional to 21.28, 29.32 and 15.81 is: 21.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.28 : 29.32 = 15.81 : x
  2. Step 2: Convert to fraction form
    21.28/29.32 = 15.81/x
  3. Step 3: Cross multiply
    21.28x = 29.32 × 15.81
  4. Step 4: Simplify right side
    21.28x = 463.47
  5. Step 5: Solve for x
    x = 463.47/21.28
  6. Step 6: Final answer
    x = 21.78

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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.