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Finding the Fourth Proportional to 129.86, 179.21 and 80.72

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Solution

The fourth proportional to 129.86, 179.21 and 80.72 is: 111.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.86 : 179.21 = 80.72 : x
  2. Step 2: Convert to fraction form
    129.86/179.21 = 80.72/x
  3. Step 3: Cross multiply
    129.86x = 179.21 × 80.72
  4. Step 4: Simplify right side
    129.86x = 14,465.83
  5. Step 5: Solve for x
    x = 14,465.83/129.86
  6. Step 6: Final answer
    x = 111.40

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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.