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Finding the Fourth Proportional to 20.50, 30.78 and 13.72

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Solution

The fourth proportional to 20.50, 30.78 and 13.72 is: 20.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.50 : 30.78 = 13.72 : x
  2. Step 2: Convert to fraction form
    20.50/30.78 = 13.72/x
  3. Step 3: Cross multiply
    20.50x = 30.78 × 13.72
  4. Step 4: Simplify right side
    20.50x = 422.30
  5. Step 5: Solve for x
    x = 422.30/20.50
  6. Step 6: Final answer
    x = 20.60

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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.