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Finding the Fourth Proportional to 20.81, 31.21 and 10.65

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Solution

The fourth proportional to 20.81, 31.21 and 10.65 is: 15.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    20.81 : 31.21 = 10.65 : x
  2. Step 2: Convert to fraction form
    20.81/31.21 = 10.65/x
  3. Step 3: Cross multiply
    20.81x = 31.21 × 10.65
  4. Step 4: Simplify right side
    20.81x = 332.39
  5. Step 5: Solve for x
    x = 332.39/20.81
  6. Step 6: Final answer
    x = 15.97

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