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Finding the Fourth Proportional to 86.16, 128.84 and 66.68

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Solution

The fourth proportional to 86.16, 128.84 and 66.68 is: 99.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.16 : 128.84 = 66.68 : x
  2. Step 2: Convert to fraction form
    86.16/128.84 = 66.68/x
  3. Step 3: Cross multiply
    86.16x = 128.84 × 66.68
  4. Step 4: Simplify right side
    86.16x = 8,591.05
  5. Step 5: Solve for x
    x = 8,591.05/86.16
  6. Step 6: Final answer
    x = 99.71

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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.