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Finding the Fourth Proportional to 161.10, 221.81 and 128.43

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Solution

The fourth proportional to 161.10, 221.81 and 128.43 is: 176.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    161.10 : 221.81 = 128.43 : x
  2. Step 2: Convert to fraction form
    161.10/221.81 = 128.43/x
  3. Step 3: Cross multiply
    161.10x = 221.81 × 128.43
  4. Step 4: Simplify right side
    161.10x = 28,486.42
  5. Step 5: Solve for x
    x = 28,486.42/161.10
  6. Step 6: Final answer
    x = 176.82

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.