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Finding the Fourth Proportional to 85.96, 128.39 and 84.64

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Solution

The fourth proportional to 85.96, 128.39 and 84.64 is: 126.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.96 : 128.39 = 84.64 : x
  2. Step 2: Convert to fraction form
    85.96/128.39 = 84.64/x
  3. Step 3: Cross multiply
    85.96x = 128.39 × 84.64
  4. Step 4: Simplify right side
    85.96x = 10,866.93
  5. Step 5: Solve for x
    x = 10,866.93/85.96
  6. Step 6: Final answer
    x = 126.42

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.