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Finding the Fourth Proportional to 87.51, 120.42 and 81.57

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Solution

The fourth proportional to 87.51, 120.42 and 81.57 is: 112.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.51 : 120.42 = 81.57 : x
  2. Step 2: Convert to fraction form
    87.51/120.42 = 81.57/x
  3. Step 3: Cross multiply
    87.51x = 120.42 × 81.57
  4. Step 4: Simplify right side
    87.51x = 9,822.66
  5. Step 5: Solve for x
    x = 9,822.66/87.51
  6. Step 6: Final answer
    x = 112.25

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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.