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Finding the Fourth Proportional to 20.53, 30.79 and 12.40

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Solution

The fourth proportional to 20.53, 30.79 and 12.40 is: 18.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.53 : 30.79 = 12.40 : x
  2. Step 2: Convert to fraction form
    20.53/30.79 = 12.40/x
  3. Step 3: Cross multiply
    20.53x = 30.79 × 12.40
  4. Step 4: Simplify right side
    20.53x = 381.66
  5. Step 5: Solve for x
    x = 381.66/20.53
  6. Step 6: Final answer
    x = 18.59

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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.