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Finding the Fourth Proportional to 128.81, 193.12 and 51.74

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Solution

The fourth proportional to 128.81, 193.12 and 51.74 is: 77.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.81 : 193.12 = 51.74 : x
  2. Step 2: Convert to fraction form
    128.81/193.12 = 51.74/x
  3. Step 3: Cross multiply
    128.81x = 193.12 × 51.74
  4. Step 4: Simplify right side
    128.81x = 9,992.74
  5. Step 5: Solve for x
    x = 9,992.74/128.81
  6. Step 6: Final answer
    x = 77.58

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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.