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Finding the Fourth Proportional to 87.89, 121.30 and 66.12

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Solution

The fourth proportional to 87.89, 121.30 and 66.12 is: 91.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.89 : 121.30 = 66.12 : x
  2. Step 2: Convert to fraction form
    87.89/121.30 = 66.12/x
  3. Step 3: Cross multiply
    87.89x = 121.30 × 66.12
  4. Step 4: Simplify right side
    87.89x = 8,020.36
  5. Step 5: Solve for x
    x = 8,020.36/87.89
  6. Step 6: Final answer
    x = 91.25

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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.