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Finding the Fourth Proportional to 30.76, 42.40 and 20.38

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Solution

The fourth proportional to 30.76, 42.40 and 20.38 is: 28.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    30.76 : 42.40 = 20.38 : x
  2. Step 2: Convert to fraction form
    30.76/42.40 = 20.38/x
  3. Step 3: Cross multiply
    30.76x = 42.40 × 20.38
  4. Step 4: Simplify right side
    30.76x = 864.11
  5. Step 5: Solve for x
    x = 864.11/30.76
  6. Step 6: Final answer
    x = 28.09

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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.