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Finding the Fourth Proportional to 87.58, 120.74 and 72.85

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Solution

The fourth proportional to 87.58, 120.74 and 72.85 is: 100.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.58 : 120.74 = 72.85 : x
  2. Step 2: Convert to fraction form
    87.58/120.74 = 72.85/x
  3. Step 3: Cross multiply
    87.58x = 120.74 × 72.85
  4. Step 4: Simplify right side
    87.58x = 8,795.88
  5. Step 5: Solve for x
    x = 8,795.88/87.58
  6. Step 6: Final answer
    x = 100.43

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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.