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Finding the Fourth Proportional to 85.38, 128.04 and 51.22

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Solution

The fourth proportional to 85.38, 128.04 and 51.22 is: 76.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.38 : 128.04 = 51.22 : x
  2. Step 2: Convert to fraction form
    85.38/128.04 = 51.22/x
  3. Step 3: Cross multiply
    85.38x = 128.04 × 51.22
  4. Step 4: Simplify right side
    85.38x = 6,558.21
  5. Step 5: Solve for x
    x = 6,558.21/85.38
  6. Step 6: Final answer
    x = 76.81

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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.