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Finding the Fourth Proportional to 77.31, 115.90 and 31.64

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Solution

The fourth proportional to 77.31, 115.90 and 31.64 is: 47.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    77.31 : 115.90 = 31.64 : x
  2. Step 2: Convert to fraction form
    77.31/115.90 = 31.64/x
  3. Step 3: Cross multiply
    77.31x = 115.90 × 31.64
  4. Step 4: Simplify right side
    77.31x = 3,667.08
  5. Step 5: Solve for x
    x = 3,667.08/77.31
  6. Step 6: Final answer
    x = 47.43

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.