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Finding the Fourth Proportional to 128.44, 192.78 and 91.91

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Solution

The fourth proportional to 128.44, 192.78 and 91.91 is: 137.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.44 : 192.78 = 91.91 : x
  2. Step 2: Convert to fraction form
    128.44/192.78 = 91.91/x
  3. Step 3: Cross multiply
    128.44x = 192.78 × 91.91
  4. Step 4: Simplify right side
    128.44x = 17,718.89
  5. Step 5: Solve for x
    x = 17,718.89/128.44
  6. Step 6: Final answer
    x = 137.96

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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.