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Finding the Fourth Proportional to 86.72, 119.69 and 81.51

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Solution

The fourth proportional to 86.72, 119.69 and 81.51 is: 112.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.72 : 119.69 = 81.51 : x
  2. Step 2: Convert to fraction form
    86.72/119.69 = 81.51/x
  3. Step 3: Cross multiply
    86.72x = 119.69 × 81.51
  4. Step 4: Simplify right side
    86.72x = 9,755.93
  5. Step 5: Solve for x
    x = 9,755.93/86.72
  6. Step 6: Final answer
    x = 112.50

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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.