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Finding the Fourth Proportional to 20.71, 28.56 and 13.42

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Solution

The fourth proportional to 20.71, 28.56 and 13.42 is: 18.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.71 : 28.56 = 13.42 : x
  2. Step 2: Convert to fraction form
    20.71/28.56 = 13.42/x
  3. Step 3: Cross multiply
    20.71x = 28.56 × 13.42
  4. Step 4: Simplify right side
    20.71x = 383.20
  5. Step 5: Solve for x
    x = 383.20/20.71
  6. Step 6: Final answer
    x = 18.51

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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.