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Finding the Fourth Proportional to 87.39, 120.78 and 79.65

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Solution

The fourth proportional to 87.39, 120.78 and 79.65 is: 110.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.39 : 120.78 = 79.65 : x
  2. Step 2: Convert to fraction form
    87.39/120.78 = 79.65/x
  3. Step 3: Cross multiply
    87.39x = 120.78 × 79.65
  4. Step 4: Simplify right side
    87.39x = 9,620.13
  5. Step 5: Solve for x
    x = 9,620.13/87.39
  6. Step 6: Final answer
    x = 110.08

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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.