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Finding the Fourth Proportional to 20.47, 28.25 and 15.31

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Solution

The fourth proportional to 20.47, 28.25 and 15.31 is: 21.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.47 : 28.25 = 15.31 : x
  2. Step 2: Convert to fraction form
    20.47/28.25 = 15.31/x
  3. Step 3: Cross multiply
    20.47x = 28.25 × 15.31
  4. Step 4: Simplify right side
    20.47x = 432.29
  5. Step 5: Solve for x
    x = 432.29/20.47
  6. Step 6: Final answer
    x = 21.12

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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.