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Finding the Fourth Proportional to 77.20, 115.87 and 31.58

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Solution

The fourth proportional to 77.20, 115.87 and 31.58 is: 47.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    77.20 : 115.87 = 31.58 : x
  2. Step 2: Convert to fraction form
    77.20/115.87 = 31.58/x
  3. Step 3: Cross multiply
    77.20x = 115.87 × 31.58
  4. Step 4: Simplify right side
    77.20x = 3,659.39
  5. Step 5: Solve for x
    x = 3,659.39/77.20
  6. Step 6: Final answer
    x = 47.40

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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.