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Finding the Fourth Proportional to 85.91, 128.72 and 63.11

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Solution

The fourth proportional to 85.91, 128.72 and 63.11 is: 94.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.91 : 128.72 = 63.11 : x
  2. Step 2: Convert to fraction form
    85.91/128.72 = 63.11/x
  3. Step 3: Cross multiply
    85.91x = 128.72 × 63.11
  4. Step 4: Simplify right side
    85.91x = 8,122.56
  5. Step 5: Solve for x
    x = 8,122.56/85.91
  6. Step 6: Final answer
    x = 94.55

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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.