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Finding the Fourth Proportional to 30.91, 42.67 and 28.86

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Solution

The fourth proportional to 30.91, 42.67 and 28.86 is: 39.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    30.91 : 42.67 = 28.86 : x
  2. Step 2: Convert to fraction form
    30.91/42.67 = 28.86/x
  3. Step 3: Cross multiply
    30.91x = 42.67 × 28.86
  4. Step 4: Simplify right side
    30.91x = 1,231.31
  5. Step 5: Solve for x
    x = 1,231.31/30.91
  6. Step 6: Final answer
    x = 39.84

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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.