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Finding the Fourth Proportional to 108.72, 163.16 and 81.60

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Solution

The fourth proportional to 108.72, 163.16 and 81.60 is: 122.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    108.72 : 163.16 = 81.60 : x
  2. Step 2: Convert to fraction form
    108.72/163.16 = 81.60/x
  3. Step 3: Cross multiply
    108.72x = 163.16 × 81.60
  4. Step 4: Simplify right side
    108.72x = 13,313.86
  5. Step 5: Solve for x
    x = 13,313.86/108.72
  6. Step 6: Final answer
    x = 122.46

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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.