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Finding the Fourth Proportional to 30.89, 42.57 and 21.68

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Solution

The fourth proportional to 30.89, 42.57 and 21.68 is: 29.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    30.89 : 42.57 = 21.68 : x
  2. Step 2: Convert to fraction form
    30.89/42.57 = 21.68/x
  3. Step 3: Cross multiply
    30.89x = 42.57 × 21.68
  4. Step 4: Simplify right side
    30.89x = 922.70
  5. Step 5: Solve for x
    x = 922.70/30.89
  6. Step 6: Final answer
    x = 29.88

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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.