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Finding the Fourth Proportional to 30.61, 42.23 and 20.89

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Solution

The fourth proportional to 30.61, 42.23 and 20.89 is: 28.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    30.61 : 42.23 = 20.89 : x
  2. Step 2: Convert to fraction form
    30.61/42.23 = 20.89/x
  3. Step 3: Cross multiply
    30.61x = 42.23 × 20.89
  4. Step 4: Simplify right side
    30.61x = 881.87
  5. Step 5: Solve for x
    x = 881.87/30.61
  6. Step 6: Final answer
    x = 28.81

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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.