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Finding the Fourth Proportional to 31.81, 47.68 and 13.78

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Solution

The fourth proportional to 31.81, 47.68 and 13.78 is: 20.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.81 : 47.68 = 13.78 : x
  2. Step 2: Convert to fraction form
    31.81/47.68 = 13.78/x
  3. Step 3: Cross multiply
    31.81x = 47.68 × 13.78
  4. Step 4: Simplify right side
    31.81x = 657.03
  5. Step 5: Solve for x
    x = 657.03/31.81
  6. Step 6: Final answer
    x = 20.65

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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.