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Finding the Fourth Proportional to 21.45, 31.95 and 20.79

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Solution

The fourth proportional to 21.45, 31.95 and 20.79 is: 30.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.45 : 31.95 = 20.79 : x
  2. Step 2: Convert to fraction form
    21.45/31.95 = 20.79/x
  3. Step 3: Cross multiply
    21.45x = 31.95 × 20.79
  4. Step 4: Simplify right side
    21.45x = 664.24
  5. Step 5: Solve for x
    x = 664.24/21.45
  6. Step 6: Final answer
    x = 30.97

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.