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Finding the Fourth Proportional to 30.81, 42.48 and 28.11

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Solution

The fourth proportional to 30.81, 42.48 and 28.11 is: 38.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    30.81 : 42.48 = 28.11 : x
  2. Step 2: Convert to fraction form
    30.81/42.48 = 28.11/x
  3. Step 3: Cross multiply
    30.81x = 42.48 × 28.11
  4. Step 4: Simplify right side
    30.81x = 1,194.11
  5. Step 5: Solve for x
    x = 1,194.11/30.81
  6. Step 6: Final answer
    x = 38.76

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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.