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Finding the Fourth Proportional to 108.90, 163.08 and 81.72

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Solution

The fourth proportional to 108.90, 163.08 and 81.72 is: 122.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    108.90 : 163.08 = 81.72 : x
  2. Step 2: Convert to fraction form
    108.90/163.08 = 81.72/x
  3. Step 3: Cross multiply
    108.90x = 163.08 × 81.72
  4. Step 4: Simplify right side
    108.90x = 13,326.90
  5. Step 5: Solve for x
    x = 13,326.90/108.90
  6. Step 6: Final answer
    x = 122.38

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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.