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Finding the Fourth Proportional to 87.69, 120.95 and 72.87

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Solution

The fourth proportional to 87.69, 120.95 and 72.87 is: 100.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.69 : 120.95 = 72.87 : x
  2. Step 2: Convert to fraction form
    87.69/120.95 = 72.87/x
  3. Step 3: Cross multiply
    87.69x = 120.95 × 72.87
  4. Step 4: Simplify right side
    87.69x = 8,813.81
  5. Step 5: Solve for x
    x = 8,813.81/87.69
  6. Step 6: Final answer
    x = 100.52

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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.