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Finding the Fourth Proportional to 129.91, 179.20 and 85.72

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Solution

The fourth proportional to 129.91, 179.20 and 85.72 is: 118.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.91 : 179.20 = 85.72 : x
  2. Step 2: Convert to fraction form
    129.91/179.20 = 85.72/x
  3. Step 3: Cross multiply
    129.91x = 179.20 × 85.72
  4. Step 4: Simplify right side
    129.91x = 15,361.02
  5. Step 5: Solve for x
    x = 15,361.02/129.91
  6. Step 6: Final answer
    x = 118.24

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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.