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Finding the Fourth Proportional to 20.70, 31.01 and 12.88

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Solution

The fourth proportional to 20.70, 31.01 and 12.88 is: 19.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.70 : 31.01 = 12.88 : x
  2. Step 2: Convert to fraction form
    20.70/31.01 = 12.88/x
  3. Step 3: Cross multiply
    20.70x = 31.01 × 12.88
  4. Step 4: Simplify right side
    20.70x = 399.25
  5. Step 5: Solve for x
    x = 399.25/20.70
  6. Step 6: Final answer
    x = 19.29

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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.