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Finding the Fourth Proportional to 220.21, 330.30 and 128.72

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Solution

The fourth proportional to 220.21, 330.30 and 128.72 is: 193.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    220.21 : 330.30 = 128.72 : x
  2. Step 2: Convert to fraction form
    220.21/330.30 = 128.72/x
  3. Step 3: Cross multiply
    220.21x = 330.30 × 128.72
  4. Step 4: Simplify right side
    220.21x = 42,517.04
  5. Step 5: Solve for x
    x = 42,517.04/220.21
  6. Step 6: Final answer
    x = 193.08

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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.