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Finding the Fourth Proportional to 87.81, 121.32 and 66.12

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Solution

The fourth proportional to 87.81, 121.32 and 66.12 is: 91.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.81 : 121.32 = 66.12 : x
  2. Step 2: Convert to fraction form
    87.81/121.32 = 66.12/x
  3. Step 3: Cross multiply
    87.81x = 121.32 × 66.12
  4. Step 4: Simplify right side
    87.81x = 8,021.68
  5. Step 5: Solve for x
    x = 8,021.68/87.81
  6. Step 6: Final answer
    x = 91.35

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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.