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Finding the Fourth Proportional to 128.65, 192.68 and 82.86

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Solution

The fourth proportional to 128.65, 192.68 and 82.86 is: 124.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.65 : 192.68 = 82.86 : x
  2. Step 2: Convert to fraction form
    128.65/192.68 = 82.86/x
  3. Step 3: Cross multiply
    128.65x = 192.68 × 82.86
  4. Step 4: Simplify right side
    128.65x = 15,965.45
  5. Step 5: Solve for x
    x = 15,965.45/128.65
  6. Step 6: Final answer
    x = 124.10

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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.