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Finding the Fourth Proportional to 128.96, 193.20 and 86.24

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Solution

The fourth proportional to 128.96, 193.20 and 86.24 is: 129.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.96 : 193.20 = 86.24 : x
  2. Step 2: Convert to fraction form
    128.96/193.20 = 86.24/x
  3. Step 3: Cross multiply
    128.96x = 193.20 × 86.24
  4. Step 4: Simplify right side
    128.96x = 16,661.57
  5. Step 5: Solve for x
    x = 16,661.57/128.96
  6. Step 6: Final answer
    x = 129.20

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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.