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Finding the Fourth Proportional to 111.87, 168.30 and 91.80

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Solution

The fourth proportional to 111.87, 168.30 and 91.80 is: 138.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    111.87 : 168.30 = 91.80 : x
  2. Step 2: Convert to fraction form
    111.87/168.30 = 91.80/x
  3. Step 3: Cross multiply
    111.87x = 168.30 × 91.80
  4. Step 4: Simplify right side
    111.87x = 15,449.94
  5. Step 5: Solve for x
    x = 15,449.94/111.87
  6. Step 6: Final answer
    x = 138.11

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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.