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Finding the Fourth Proportional to 72.81, 109.18 and 31.68

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Solution

The fourth proportional to 72.81, 109.18 and 31.68 is: 47.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    72.81 : 109.18 = 31.68 : x
  2. Step 2: Convert to fraction form
    72.81/109.18 = 31.68/x
  3. Step 3: Cross multiply
    72.81x = 109.18 × 31.68
  4. Step 4: Simplify right side
    72.81x = 3,458.74
  5. Step 5: Solve for x
    x = 3,458.74/72.81
  6. Step 6: Final answer
    x = 47.50

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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.