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Finding the Fourth Proportional to 128.86, 193.30 and 55.72

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Solution

The fourth proportional to 128.86, 193.30 and 55.72 is: 83.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.86 : 193.30 = 55.72 : x
  2. Step 2: Convert to fraction form
    128.86/193.30 = 55.72/x
  3. Step 3: Cross multiply
    128.86x = 193.30 × 55.72
  4. Step 4: Simplify right side
    128.86x = 10,770.68
  5. Step 5: Solve for x
    x = 10,770.68/128.86
  6. Step 6: Final answer
    x = 83.58

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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.