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Finding the Fourth Proportional to 31.12, 42.88 and 25.87

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Solution

The fourth proportional to 31.12, 42.88 and 25.87 is: 35.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.12 : 42.88 = 25.87 : x
  2. Step 2: Convert to fraction form
    31.12/42.88 = 25.87/x
  3. Step 3: Cross multiply
    31.12x = 42.88 × 25.87
  4. Step 4: Simplify right side
    31.12x = 1,109.26
  5. Step 5: Solve for x
    x = 1,109.26/31.12
  6. Step 6: Final answer
    x = 35.65

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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.