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Finding the Fourth Proportional to 87.66, 121 and 54.90

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Solution

The fourth proportional to 87.66, 121 and 54.90 is: 75.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.66 : 121 = 54.90 : x
  2. Step 2: Convert to fraction form
    87.66/121 = 54.90/x
  3. Step 3: Cross multiply
    87.66x = 121 × 54.90
  4. Step 4: Simplify right side
    87.66x = 6,642.90
  5. Step 5: Solve for x
    x = 6,642.90/87.66
  6. Step 6: Final answer
    x = 75.78

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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.