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Finding the Fourth Proportional to 123.12, 169.86 and 81.72

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Solution

The fourth proportional to 123.12, 169.86 and 81.72 is: 112.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    123.12 : 169.86 = 81.72 : x
  2. Step 2: Convert to fraction form
    123.12/169.86 = 81.72/x
  3. Step 3: Cross multiply
    123.12x = 169.86 × 81.72
  4. Step 4: Simplify right side
    123.12x = 13,880.96
  5. Step 5: Solve for x
    x = 13,880.96/123.12
  6. Step 6: Final answer
    x = 112.74

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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.