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Finding the Fourth Proportional to 128.28, 192.24 and 103.86

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Solution

The fourth proportional to 128.28, 192.24 and 103.86 is: 155.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.28 : 192.24 = 103.86 : x
  2. Step 2: Convert to fraction form
    128.28/192.24 = 103.86/x
  3. Step 3: Cross multiply
    128.28x = 192.24 × 103.86
  4. Step 4: Simplify right side
    128.28x = 19,966.05
  5. Step 5: Solve for x
    x = 19,966.05/128.28
  6. Step 6: Final answer
    x = 155.64

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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.