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Finding the Fourth Proportional to 31.13, 42.87 and 28.95

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Solution

The fourth proportional to 31.13, 42.87 and 28.95 is: 39.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.13 : 42.87 = 28.95 : x
  2. Step 2: Convert to fraction form
    31.13/42.87 = 28.95/x
  3. Step 3: Cross multiply
    31.13x = 42.87 × 28.95
  4. Step 4: Simplify right side
    31.13x = 1,241.09
  5. Step 5: Solve for x
    x = 1,241.09/31.13
  6. Step 6: Final answer
    x = 39.87

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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.