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Finding the Fourth Proportional to 72.12, 108.20 and 31.56

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Solution

The fourth proportional to 72.12, 108.20 and 31.56 is: 47.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    72.12 : 108.20 = 31.56 : x
  2. Step 2: Convert to fraction form
    72.12/108.20 = 31.56/x
  3. Step 3: Cross multiply
    72.12x = 108.20 × 31.56
  4. Step 4: Simplify right side
    72.12x = 3,414.47
  5. Step 5: Solve for x
    x = 3,414.47/72.12
  6. Step 6: Final answer
    x = 47.34

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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.