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Finding the Fourth Proportional to 221.17, 331.80 and 91.21

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Solution

The fourth proportional to 221.17, 331.80 and 91.21 is: 136.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    221.17 : 331.80 = 91.21 : x
  2. Step 2: Convert to fraction form
    221.17/331.80 = 91.21/x
  3. Step 3: Cross multiply
    221.17x = 331.80 × 91.21
  4. Step 4: Simplify right side
    221.17x = 30,263.48
  5. Step 5: Solve for x
    x = 30,263.48/221.17
  6. Step 6: Final answer
    x = 136.83

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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.