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Finding the Fourth Proportional to 87.55, 120.70 and 61.28

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Solution

The fourth proportional to 87.55, 120.70 and 61.28 is: 84.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.55 : 120.70 = 61.28 : x
  2. Step 2: Convert to fraction form
    87.55/120.70 = 61.28/x
  3. Step 3: Cross multiply
    87.55x = 120.70 × 61.28
  4. Step 4: Simplify right side
    87.55x = 7,396.42
  5. Step 5: Solve for x
    x = 7,396.42/87.55
  6. Step 6: Final answer
    x = 84.48

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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.