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Finding the Fourth Proportional to 115.20, 158.60 and 87.39

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Solution

The fourth proportional to 115.20, 158.60 and 87.39 is: 120.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    115.20 : 158.60 = 87.39 : x
  2. Step 2: Convert to fraction form
    115.20/158.60 = 87.39/x
  3. Step 3: Cross multiply
    115.20x = 158.60 × 87.39
  4. Step 4: Simplify right side
    115.20x = 13,859.62
  5. Step 5: Solve for x
    x = 13,859.62/115.20
  6. Step 6: Final answer
    x = 120.31

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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.