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Finding the Fourth Proportional to 129.45, 178.79 and 115.64

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Solution

The fourth proportional to 129.45, 178.79 and 115.64 is: 159.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.45 : 178.79 = 115.64 : x
  2. Step 2: Convert to fraction form
    129.45/178.79 = 115.64/x
  3. Step 3: Cross multiply
    129.45x = 178.79 × 115.64
  4. Step 4: Simplify right side
    129.45x = 20,675.28
  5. Step 5: Solve for x
    x = 20,675.28/129.45
  6. Step 6: Final answer
    x = 159.72

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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.