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Finding the Fourth Proportional to 172.70, 258.96 and 81.47

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Solution

The fourth proportional to 172.70, 258.96 and 81.47 is: 122.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    172.70 : 258.96 = 81.47 : x
  2. Step 2: Convert to fraction form
    172.70/258.96 = 81.47/x
  3. Step 3: Cross multiply
    172.70x = 258.96 × 81.47
  4. Step 4: Simplify right side
    172.70x = 21,098.42
  5. Step 5: Solve for x
    x = 21,098.42/172.70
  6. Step 6: Final answer
    x = 122.17

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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.