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Finding the Fourth Proportional to 154.20, 231.38 and 85.68

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Solution

The fourth proportional to 154.20, 231.38 and 85.68 is: 128.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    154.20 : 231.38 = 85.68 : x
  2. Step 2: Convert to fraction form
    154.20/231.38 = 85.68/x
  3. Step 3: Cross multiply
    154.20x = 231.38 × 85.68
  4. Step 4: Simplify right side
    154.20x = 19,824.64
  5. Step 5: Solve for x
    x = 19,824.64/154.20
  6. Step 6: Final answer
    x = 128.56

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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.