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Finding the Fourth Proportional to 87.89, 121.30 and 55.15

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Solution

The fourth proportional to 87.89, 121.30 and 55.15 is: 76.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.89 : 121.30 = 55.15 : x
  2. Step 2: Convert to fraction form
    87.89/121.30 = 55.15/x
  3. Step 3: Cross multiply
    87.89x = 121.30 × 55.15
  4. Step 4: Simplify right side
    87.89x = 6,689.25
  5. Step 5: Solve for x
    x = 6,689.25/87.89
  6. Step 6: Final answer
    x = 76.11

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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.