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Finding the Fourth Proportional to 72.31, 108.40 and 31.74

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Solution

The fourth proportional to 72.31, 108.40 and 31.74 is: 47.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    72.31 : 108.40 = 31.74 : x
  2. Step 2: Convert to fraction form
    72.31/108.40 = 31.74/x
  3. Step 3: Cross multiply
    72.31x = 108.40 × 31.74
  4. Step 4: Simplify right side
    72.31x = 3,440.62
  5. Step 5: Solve for x
    x = 3,440.62/72.31
  6. Step 6: Final answer
    x = 47.58

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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.