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Finding the Fourth Proportional to 111.57, 167.19 and 85.90

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Solution

The fourth proportional to 111.57, 167.19 and 85.90 is: 128.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    111.57 : 167.19 = 85.90 : x
  2. Step 2: Convert to fraction form
    111.57/167.19 = 85.90/x
  3. Step 3: Cross multiply
    111.57x = 167.19 × 85.90
  4. Step 4: Simplify right side
    111.57x = 14,361.62
  5. Step 5: Solve for x
    x = 14,361.62/111.57
  6. Step 6: Final answer
    x = 128.72

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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.