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Finding the Fourth Proportional to 42.09, 63.13 and 21.79

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Solution

The fourth proportional to 42.09, 63.13 and 21.79 is: 32.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.09 : 63.13 = 21.79 : x
  2. Step 2: Convert to fraction form
    42.09/63.13 = 21.79/x
  3. Step 3: Cross multiply
    42.09x = 63.13 × 21.79
  4. Step 4: Simplify right side
    42.09x = 1,375.31
  5. Step 5: Solve for x
    x = 1,375.31/42.09
  6. Step 6: Final answer
    x = 32.68

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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.