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Finding the Fourth Proportional to 129.40, 178.56 and 80.28

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Solution

The fourth proportional to 129.40, 178.56 and 80.28 is: 110.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.40 : 178.56 = 80.28 : x
  2. Step 2: Convert to fraction form
    129.40/178.56 = 80.28/x
  3. Step 3: Cross multiply
    129.40x = 178.56 × 80.28
  4. Step 4: Simplify right side
    129.40x = 14,334.80
  5. Step 5: Solve for x
    x = 14,334.80/129.40
  6. Step 6: Final answer
    x = 110.78

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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.