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Finding the Fourth Proportional to 172.99, 259.21 and 81.55

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Solution

The fourth proportional to 172.99, 259.21 and 81.55 is: 122.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    172.99 : 259.21 = 81.55 : x
  2. Step 2: Convert to fraction form
    172.99/259.21 = 81.55/x
  3. Step 3: Cross multiply
    172.99x = 259.21 × 81.55
  4. Step 4: Simplify right side
    172.99x = 21,138.58
  5. Step 5: Solve for x
    x = 21,138.58/172.99
  6. Step 6: Final answer
    x = 122.20

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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.