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Finding the Fourth Proportional to 86.09, 128.88 and 68.85

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Solution

The fourth proportional to 86.09, 128.88 and 68.85 is: 103.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.09 : 128.88 = 68.85 : x
  2. Step 2: Convert to fraction form
    86.09/128.88 = 68.85/x
  3. Step 3: Cross multiply
    86.09x = 128.88 × 68.85
  4. Step 4: Simplify right side
    86.09x = 8,873.39
  5. Step 5: Solve for x
    x = 8,873.39/86.09
  6. Step 6: Final answer
    x = 103.08

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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.