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Finding the Fourth Proportional to 172.45, 258.61 and 81.12

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Solution

The fourth proportional to 172.45, 258.61 and 81.12 is: 121.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    172.45 : 258.61 = 81.12 : x
  2. Step 2: Convert to fraction form
    172.45/258.61 = 81.12/x
  3. Step 3: Cross multiply
    172.45x = 258.61 × 81.12
  4. Step 4: Simplify right side
    172.45x = 20,978.44
  5. Step 5: Solve for x
    x = 20,978.44/172.45
  6. Step 6: Final answer
    x = 121.65

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.