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Finding the Fourth Proportional to 20.31, 28.02 and 15.40

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Solution

The fourth proportional to 20.31, 28.02 and 15.40 is: 21.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.31 : 28.02 = 15.40 : x
  2. Step 2: Convert to fraction form
    20.31/28.02 = 15.40/x
  3. Step 3: Cross multiply
    20.31x = 28.02 × 15.40
  4. Step 4: Simplify right side
    20.31x = 431.60
  5. Step 5: Solve for x
    x = 431.60/20.31
  6. Step 6: Final answer
    x = 21.25

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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.