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Finding the Fourth Proportional to 128.62, 192.69 and 87.91

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Solution

The fourth proportional to 128.62, 192.69 and 87.91 is: 131.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.62 : 192.69 = 87.91 : x
  2. Step 2: Convert to fraction form
    128.62/192.69 = 87.91/x
  3. Step 3: Cross multiply
    128.62x = 192.69 × 87.91
  4. Step 4: Simplify right side
    128.62x = 16,939.38
  5. Step 5: Solve for x
    x = 16,939.38/128.62
  6. Step 6: Final answer
    x = 131.70

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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.