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Finding the Fourth Proportional to 30.38, 42.12 and 28.55

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Solution

The fourth proportional to 30.38, 42.12 and 28.55 is: 39.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    30.38 : 42.12 = 28.55 : x
  2. Step 2: Convert to fraction form
    30.38/42.12 = 28.55/x
  3. Step 3: Cross multiply
    30.38x = 42.12 × 28.55
  4. Step 4: Simplify right side
    30.38x = 1,202.63
  5. Step 5: Solve for x
    x = 1,202.63/30.38
  6. Step 6: Final answer
    x = 39.59

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.