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Finding the Fourth Proportional to 172.87, 258.94 and 81.51

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Solution

The fourth proportional to 172.87, 258.94 and 81.51 is: 122.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    172.87 : 258.94 = 81.51 : x
  2. Step 2: Convert to fraction form
    172.87/258.94 = 81.51/x
  3. Step 3: Cross multiply
    172.87x = 258.94 × 81.51
  4. Step 4: Simplify right side
    172.87x = 21,106.20
  5. Step 5: Solve for x
    x = 21,106.20/172.87
  6. Step 6: Final answer
    x = 122.09

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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.