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Finding the Fourth Proportional to 172.79, 259.11 and 86.09

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Solution

The fourth proportional to 172.79, 259.11 and 86.09 is: 129.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    172.79 : 259.11 = 86.09 : x
  2. Step 2: Convert to fraction form
    172.79/259.11 = 86.09/x
  3. Step 3: Cross multiply
    172.79x = 259.11 × 86.09
  4. Step 4: Simplify right side
    172.79x = 22,307.18
  5. Step 5: Solve for x
    x = 22,307.18/172.79
  6. Step 6: Final answer
    x = 129.10

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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.