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Finding the Fourth Proportional to 69.21, 103.80 and 20.45

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Solution

The fourth proportional to 69.21, 103.80 and 20.45 is: 30.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    69.21 : 103.80 = 20.45 : x
  2. Step 2: Convert to fraction form
    69.21/103.80 = 20.45/x
  3. Step 3: Cross multiply
    69.21x = 103.80 × 20.45
  4. Step 4: Simplify right side
    69.21x = 2,122.71
  5. Step 5: Solve for x
    x = 2,122.71/69.21
  6. Step 6: Final answer
    x = 30.67

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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.