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Finding the Fourth Proportional to 87.70, 120.97 and 61.78

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Solution

The fourth proportional to 87.70, 120.97 and 61.78 is: 85.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.70 : 120.97 = 61.78 : x
  2. Step 2: Convert to fraction form
    87.70/120.97 = 61.78/x
  3. Step 3: Cross multiply
    87.70x = 120.97 × 61.78
  4. Step 4: Simplify right side
    87.70x = 7,473.53
  5. Step 5: Solve for x
    x = 7,473.53/87.70
  6. Step 6: Final answer
    x = 85.22

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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.