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Finding the Fourth Proportional to 87.30, 121.39 and 86.76

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Solution

The fourth proportional to 87.30, 121.39 and 86.76 is: 120.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.30 : 121.39 = 86.76 : x
  2. Step 2: Convert to fraction form
    87.30/121.39 = 86.76/x
  3. Step 3: Cross multiply
    87.30x = 121.39 × 86.76
  4. Step 4: Simplify right side
    87.30x = 10,531.58
  5. Step 5: Solve for x
    x = 10,531.58/87.30
  6. Step 6: Final answer
    x = 120.64

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.