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Finding the Fourth Proportional to 87.57, 120.79 and 66.80

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Solution

The fourth proportional to 87.57, 120.79 and 66.80 is: 92.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.57 : 120.79 = 66.80 : x
  2. Step 2: Convert to fraction form
    87.57/120.79 = 66.80/x
  3. Step 3: Cross multiply
    87.57x = 120.79 × 66.80
  4. Step 4: Simplify right side
    87.57x = 8,069.16
  5. Step 5: Solve for x
    x = 8,069.16/87.57
  6. Step 6: Final answer
    x = 92.15

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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.