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Finding the Fourth Proportional to 87.96, 121.31 and 66.19

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Solution

The fourth proportional to 87.96, 121.31 and 66.19 is: 91.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.96 : 121.31 = 66.19 : x
  2. Step 2: Convert to fraction form
    87.96/121.31 = 66.19/x
  3. Step 3: Cross multiply
    87.96x = 121.31 × 66.19
  4. Step 4: Simplify right side
    87.96x = 8,029.18
  5. Step 5: Solve for x
    x = 8,029.18/87.96
  6. Step 6: Final answer
    x = 91.29

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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.