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Finding the Fourth Proportional to 172.21, 258.15 and 91.11

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Solution

The fourth proportional to 172.21, 258.15 and 91.11 is: 136.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    172.21 : 258.15 = 91.11 : x
  2. Step 2: Convert to fraction form
    172.21/258.15 = 91.11/x
  3. Step 3: Cross multiply
    172.21x = 258.15 × 91.11
  4. Step 4: Simplify right side
    172.21x = 23,520.05
  5. Step 5: Solve for x
    x = 23,520.05/172.21
  6. Step 6: Final answer
    x = 136.58

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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.