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Finding the Fourth Proportional to 20.51, 30.76 and 12.91

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Solution

The fourth proportional to 20.51, 30.76 and 12.91 is: 19.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.51 : 30.76 = 12.91 : x
  2. Step 2: Convert to fraction form
    20.51/30.76 = 12.91/x
  3. Step 3: Cross multiply
    20.51x = 30.76 × 12.91
  4. Step 4: Simplify right side
    20.51x = 396.96
  5. Step 5: Solve for x
    x = 396.96/20.51
  6. Step 6: Final answer
    x = 19.35

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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.