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Finding the Fourth Proportional to 105.21, 145.38 and 81.96

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Solution

The fourth proportional to 105.21, 145.38 and 81.96 is: 113.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    105.21 : 145.38 = 81.96 : x
  2. Step 2: Convert to fraction form
    105.21/145.38 = 81.96/x
  3. Step 3: Cross multiply
    105.21x = 145.38 × 81.96
  4. Step 4: Simplify right side
    105.21x = 11,914.65
  5. Step 5: Solve for x
    x = 11,914.65/105.21
  6. Step 6: Final answer
    x = 113.25

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.