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Finding the Fourth Proportional to 20.86, 28.80 and 15.67

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Solution

The fourth proportional to 20.86, 28.80 and 15.67 is: 21.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.86 : 28.80 = 15.67 : x
  2. Step 2: Convert to fraction form
    20.86/28.80 = 15.67/x
  3. Step 3: Cross multiply
    20.86x = 28.80 × 15.67
  4. Step 4: Simplify right side
    20.86x = 451.30
  5. Step 5: Solve for x
    x = 451.30/20.86
  6. Step 6: Final answer
    x = 21.63

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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.