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Finding the Fourth Proportional to 85.76, 128.44 and 84.35

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Solution

The fourth proportional to 85.76, 128.44 and 84.35 is: 126.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.76 : 128.44 = 84.35 : x
  2. Step 2: Convert to fraction form
    85.76/128.44 = 84.35/x
  3. Step 3: Cross multiply
    85.76x = 128.44 × 84.35
  4. Step 4: Simplify right side
    85.76x = 10,833.91
  5. Step 5: Solve for x
    x = 10,833.91/85.76
  6. Step 6: Final answer
    x = 126.33

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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.