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Finding the Fourth Proportional to 221.39, 305.42 and 128.13

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Solution

The fourth proportional to 221.39, 305.42 and 128.13 is: 176.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    221.39 : 305.42 = 128.13 : x
  2. Step 2: Convert to fraction form
    221.39/305.42 = 128.13/x
  3. Step 3: Cross multiply
    221.39x = 305.42 × 128.13
  4. Step 4: Simplify right side
    221.39x = 39,133.46
  5. Step 5: Solve for x
    x = 39,133.46/221.39
  6. Step 6: Final answer
    x = 176.76

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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.