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Finding the Fourth Proportional to 87.39, 131.18 and 78.69

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Solution

The fourth proportional to 87.39, 131.18 and 78.69 is: 118.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.39 : 131.18 = 78.69 : x
  2. Step 2: Convert to fraction form
    87.39/131.18 = 78.69/x
  3. Step 3: Cross multiply
    87.39x = 131.18 × 78.69
  4. Step 4: Simplify right side
    87.39x = 10,322.16
  5. Step 5: Solve for x
    x = 10,322.16/87.39
  6. Step 6: Final answer
    x = 118.12

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.