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Finding the Fourth Proportional to 31.07, 42.84 and 20.15

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Solution

The fourth proportional to 31.07, 42.84 and 20.15 is: 27.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.07 : 42.84 = 20.15 : x
  2. Step 2: Convert to fraction form
    31.07/42.84 = 20.15/x
  3. Step 3: Cross multiply
    31.07x = 42.84 × 20.15
  4. Step 4: Simplify right side
    31.07x = 863.01
  5. Step 5: Solve for x
    x = 863.01/31.07
  6. Step 6: Final answer
    x = 27.78

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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.