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Finding the Fourth Proportional to 87.39, 120.60 and 61.20

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Solution

The fourth proportional to 87.39, 120.60 and 61.20 is: 84.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.39 : 120.60 = 61.20 : x
  2. Step 2: Convert to fraction form
    87.39/120.60 = 61.20/x
  3. Step 3: Cross multiply
    87.39x = 120.60 × 61.20
  4. Step 4: Simplify right side
    87.39x = 7,380.72
  5. Step 5: Solve for x
    x = 7,380.72/87.39
  6. Step 6: Final answer
    x = 84.46

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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.