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Finding the Fourth Proportional to 108.72, 162.21 and 86.66

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Solution

The fourth proportional to 108.72, 162.21 and 86.66 is: 129.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    108.72 : 162.21 = 86.66 : x
  2. Step 2: Convert to fraction form
    108.72/162.21 = 86.66/x
  3. Step 3: Cross multiply
    108.72x = 162.21 × 86.66
  4. Step 4: Simplify right side
    108.72x = 14,056.31
  5. Step 5: Solve for x
    x = 14,056.31/108.72
  6. Step 6: Final answer
    x = 129.29

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.