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Finding the Fourth Proportional to 87.18, 120.21 and 72.50

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Solution

The fourth proportional to 87.18, 120.21 and 72.50 is: 99.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.18 : 120.21 = 72.50 : x
  2. Step 2: Convert to fraction form
    87.18/120.21 = 72.50/x
  3. Step 3: Cross multiply
    87.18x = 120.21 × 72.50
  4. Step 4: Simplify right side
    87.18x = 8,714.62
  5. Step 5: Solve for x
    x = 8,714.62/87.18
  6. Step 6: Final answer
    x = 99.96

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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.