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Finding the Fourth Proportional to 221.45, 305.51 and 128.18

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Solution

The fourth proportional to 221.45, 305.51 and 128.18 is: 176.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    221.45 : 305.51 = 128.18 : x
  2. Step 2: Convert to fraction form
    221.45/305.51 = 128.18/x
  3. Step 3: Cross multiply
    221.45x = 305.51 × 128.18
  4. Step 4: Simplify right side
    221.45x = 39,158.42
  5. Step 5: Solve for x
    x = 39,158.42/221.45
  6. Step 6: Final answer
    x = 176.83

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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.