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Finding the Fourth Proportional to 20.85, 28.74 and 15.67

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Solution

The fourth proportional to 20.85, 28.74 and 15.67 is: 21.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.85 : 28.74 = 15.67 : x
  2. Step 2: Convert to fraction form
    20.85/28.74 = 15.67/x
  3. Step 3: Cross multiply
    20.85x = 28.74 × 15.67
  4. Step 4: Simplify right side
    20.85x = 450.36
  5. Step 5: Solve for x
    x = 450.36/20.85
  6. Step 6: Final answer
    x = 21.60

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.