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Finding the Fourth Proportional to 20.88, 31.30 and 12.31

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Solution

The fourth proportional to 20.88, 31.30 and 12.31 is: 18.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.88 : 31.30 = 12.31 : x
  2. Step 2: Convert to fraction form
    20.88/31.30 = 12.31/x
  3. Step 3: Cross multiply
    20.88x = 31.30 × 12.31
  4. Step 4: Simplify right side
    20.88x = 385.30
  5. Step 5: Solve for x
    x = 385.30/20.88
  6. Step 6: Final answer
    x = 18.45

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.