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Finding the Fourth Proportional to 129.45, 178.64 and 77.70

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Solution

The fourth proportional to 129.45, 178.64 and 77.70 is: 107.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.45 : 178.64 = 77.70 : x
  2. Step 2: Convert to fraction form
    129.45/178.64 = 77.70/x
  3. Step 3: Cross multiply
    129.45x = 178.64 × 77.70
  4. Step 4: Simplify right side
    129.45x = 13,880.33
  5. Step 5: Solve for x
    x = 13,880.33/129.45
  6. Step 6: Final answer
    x = 107.23

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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.