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Finding the Fourth Proportional to 129.76, 178.48 and 121.12

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Solution

The fourth proportional to 129.76, 178.48 and 121.12 is: 166.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    129.76 : 178.48 = 121.12 : x
  2. Step 2: Convert to fraction form
    129.76/178.48 = 121.12/x
  3. Step 3: Cross multiply
    129.76x = 178.48 × 121.12
  4. Step 4: Simplify right side
    129.76x = 21,617.50
  5. Step 5: Solve for x
    x = 21,617.50/129.76
  6. Step 6: Final answer
    x = 166.60

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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.